The Most Effective Tips for Koi Pond Maintenance

koi pond water testing

Koi Pond Water Testing

Having a Koi pond at your home is undoubtedly the quickest way to reduce stress and anxiety that you have to deal with on a regular basis. This peaceful and quiet place is essentially a man-made paradise. Apart from eliminating stress and tension of your mind, a Koi pond is a perfect way of adding beauty to your backyard or any outdoor space.  However, it requires some effort to keep it in its healthiest and most attractive condition. You may have heard that building a Koi pond is a much easier task as compared to maintaining it. However, if you take proper care of your Koi pond right from the beginning, you can avoid many complications later on. With that in mind, let’s take a look at some of the most simple and effective precautionary steps that you can employ to keep your Koi pond healthy.

Perform constant water checks to avoid common problems

Koi pond owners may have to deal with issues like acid rain, excessive fish waste and nutrient-enriched runoff.  In order to stay on top of these common but serious issues, it is highly advisable to perform constant water checks. Although it’s true that Koi fish can be easily taken care of, poor water quality can cause even the hardiest fish to suffer from health issues.

Maintain the right temperature

People living in colder regions where ponds freeze over shouldn’t worry-they will be relieved to discover that Koi can survive during the winter months . When ice forms on the surface, these fish can essentially hibernate under the surface. In order to be on the safer side you can use a floating de-icer to maintain the a hole in the ice for proper gas exchange.


Avoid overfeeding

Over feeding your Koi is one of the most common yet unhealthiest mistakes made by well-intentioned koi owners. When feeding you should take that opportunity to evaluate your Koi closely. This will help you to detect any diseases or injuries that have occurred to the fish. Overfeeding can lead to poor water quality which itself can initiate a host of  additional problems down the road.  These problems include high ammonia and nitrites in the water which can translate into fin rot, parasites and other diseases


Properly maintain all your Koi pond equipment

This equipment normally includes a good quality filtration system, a powerful pump, protein skimmer, aeration system and ultraviolet sterilizer. For instance, the pond pump is used for pumping water in and out of the pond which aids in maintaining proper water movement in the pond.


The filtration system in combination with the protein skimmer is very useful in keeping the surface water clean. As mentioned previously, a floating de-icer can be useful in maintaining proper gas exchange in the pond during the colder months.


There is no doubt that Koi fish are one of the most graceful aquatic pets.  In fact, in the US koi are the most common fish pet. Interestingly,  they also have an fairly decent life span (you can expect 15-20 years and in some cases much longer). However, if you don’t take proper care of them, they won’t be able to live to their potential.

For a more comprehensive coverage of koi maintenance click here.

By |2017-12-01T02:45:10+00:00November 8th, 2012|General Koi Information|165 Comments

About the Author:

I have been interested in fish for over 25 years. I have two degrees in marine science with a specialization in fish ecology and physiology (as well as a chemistry minor). Like many kids, I had a goldfish growing up but decades later took care of several koi ponds. Koi are such great pets and very accessible for many folks wanting to get into owning koi in a pond environment.


  1. Mary June 4, 2013 at 8:38 pm - Reply

    We have a backyard Koi pond that we installed several years ago and have had no problems until this last month or so,now our fish are at the edge of the pond where the water fall flows and seem to be having problems getting air.We do have about 50 midium size fry now for the first time,they appeared late last summer and wintered over well,we have 7 large size Koi.
    We don’t know what to do.

    • Koi-Care staff June 9, 2013 at 6:00 pm - Reply

      Okay, so it sounds like you have a low DO problem (dissolved oxygen). Koi DO requirements are around 6 mg/l so there could be a few things going on. You could be experiencing excessive nutrient loads in the water which would cause increased growth of algae which in the short term creates more DO but once that algae dies it decays and that decaying process depletes oxygen which may describe your situation. You may have had a really hot summer and warmer water holds less DO than cooler water or you may have an increased oxygen requirement in your pond by having the fry in there and your aeration systems are inadequate to meet the increased demand. In short I would check DO levels as well as phosphorus and nitrate levels. If need be you may have to install more aeration equipment to increase DO.
      Thanks for stopping by.

  2. Jennifer Nelson July 5, 2013 at 1:19 pm - Reply

    We just bought a house that we knew had a water feature, but I discovered yesterday that there are koi in the small pond part of the water feature. The house had been vacant for over a year until we moved in last week. Will it shock the fish if we start trying to clean up the pond, or I guess the question would be, where do we start in trying to care for these fish? We are so excited about them, and want them to be happy and healthy!

    • Koi-Care staff July 5, 2013 at 4:53 pm - Reply

      Congratulations -that’s always nice when you get an added bonus when buying property. Well, if they haven’t been tended to for a year then SOMEthing is going right! I don’t know what kind of systems are already in place at the pond such as filtration or aeration but I would suggest starting with a basic water testing kit -it won’t be complicated to make sure your water remains in the correct balance. I would almost be tempted to suggest not doing much to the pond if you already have content and thriving koi. You may want to do some supplemental feeding with koi chow though. If you decide to really ramp it up and want more koi or a bigger pond I offer a pretty comprehensive koi manual on my site that covers everything you’ll need to know.
      Good luck and congratulations!

      • Jennifer Nelson July 8, 2013 at 2:36 pm - Reply

        Thank you so much! I did buy some koi food, which they seem to really enjoy – especially the big one, who pushes away the little ones to get the pellets! I found a manual for a uv filter, and there is filter cleaning solution in the laundry room. There is a small waterfall that we hope to get up and running within the next two weeks while my husband is home on a short break from being on the road. Here is my next item – there is some other kind of creature living with the koi, and I’m hoping you can help me figure out what it is… It is black, with eyes on top of its head, and he comes to the surface every once in a while and puts his eyes above the water. He is very skittish, so I don’t get a very good look at him before he disappears. I was thinking mudskipper until I learned they like salty water. Now I’m thinking some kind of frog, I guess, but I don’t know if frogs can stay underwater as long as this guy does. Any thoughts? 🙂 Thanks for your help with the koi – I am definitely going to get a pH kit, but I will try not to upset what they already have going on in the pond, since it does seem to be working, like you said. Take care!

        • Leslie July 22, 2013 at 6:36 pm - Reply

          How strange, I am in almost exactly the same situation as you! We also bought a house (in February) with a little pond with 17 fish (I think they are goldfish, not koi). This pond also had not been maintained – but not for just a year, for the entire time it has been there. The previous owner straight-up said he did nothing to maintain it. There is about a foot of sludge/pine needles/leaves/sticks/pine cones in the bottom. There was a LOT more (water was so dirty we literally couldn’t see the bottom). We are gradually hacking away at it but every time we go at it with nets, it throws up a lot of silt into the water. We’ve been using a pump/filter, good bacteria capsules on the filter, and some good anti-sludge bacteria stuff so we can at least see the bottom now. I’ve seen some kind of stuff you can put in the water that’s supposed to clear it up, but I am worried about adding too much stuff to the pond for the same reason Koi-Care said; it managed to survive somehow and I might throw off whatever balance is there. BUT it was FILTHY and I’m sure in general not good for the fish. Plus, we have tried feeding them, but they completely ignore any food and I see them stick their heads in the sludgey stuff and wriggle around, so I think they are managing to eat out of it. We lost 1/3 of the fish recently (I think the pest control sprayed our nets) and have added three koi just this past weekend. After three days they are still swimming around and getting along with the other fish. So sorry, I just wanted to share, guess I don’t really have a question. 🙂

  3. Dwain August 3, 2013 at 5:35 pm - Reply

    Koi pond we adopted last season is mature with Koi having grown very large( 4 of the 7 over 18″ long)…I noticed lately they do not come to the top for food anymore but when I walk back out to the pond later food is gone. They used to watch me come up to pond and then aggressively feed on food. Now they tend to stay swimming lower in pond and ignoring my feeding so that is a concern in that they have changed their behavior thus so……any thing come to mind as for the cause in behavior towards feeding?

    • Koi-Care staff August 5, 2013 at 2:12 pm - Reply

      My best guess would be that they are associating your presence with perhaps the presence of something else like raccoons or wading birds that may be attempting to prey on your koi. You may also have some neighborhood kids hanging out at your pond throwing rocks at the fish (though I don’t know if you have neighbors or what the layout of your property is). Hope this helps

  4. Glenys chen September 11, 2013 at 3:12 am - Reply

    We have a 2600 gallon pond and have 12 XXlarge Koi in the pond. Is that too many? Ans will they survive. We also have a 2000 gallon bubbler going on, so hoped that helps. Can we put more fish in? Each of the fish is nearly 30″ long. Thank you my pond is only 3 1/2 ft deep. Will they do well in winter.?

    • Koi-Care staff September 12, 2013 at 2:19 pm - Reply

      I would give it some time and be sure to check the water quality -a
      lot of metabolic activity via the fish can change nitrate and nitrite
      levels. I don’t know that I would go much beyond that number of fish
      though. In my experience, fish that aren’t crowded do much better.
      As far as winter goes they should be fine, koi/carp are adapted to
      over-winter without a problem. your depth seems fine to me. Try not
      to over feed as that can create problems with excessive nutrients in
      the water. Submerged plants are always nice too for a place to
      shelter up for koi and get shade in the summer as well as provide
      dissolved oxygen in the water.

  5. Carol Bell September 30, 2013 at 7:16 pm - Reply

    This Spring, we bought a house with a Coy Pond and Waterfall
    in the backyard. After moving into the house, we had a
    professional pondman come and clean our pond. We also had to
    purchase a new circulating pump. The water had previously
    been extremely cloudy. After the cleaning the water stayed
    clear (could see to the bottom) for about a week. Then it
    began to get mucky again. The pondman suggested that we buy
    some more water lilies to keep it clean. We did that, but it
    did not seem to help much. Now the water is very mucky again.
    We cannot see the fish except when they come up to eat. And
    the top of the water has a scummy film. What do we do???
    We have about 7 gold fish, some kind of medium size white
    fish (1), and 1 large white catfish.

    • Koi-Care staff October 3, 2013 at 1:29 pm - Reply

      so it sounds like your fish are actually doing okay. My guess is that
      even after getting your pond cleaned out that you still have a great
      deal of unconsolidated muck in your pond that is getting disturbed and
      gettting mixed into the water column. Another possibility is that the
      cleaning triggered an algal bloom perhaps and that is clouding up the
      water. It may just be a matter of time before that bloom dies and
      your water clarity is regained. If your pond cleaning guy really did
      clean out all the muck then there should be no way that there is any
      more muck to be suspended unless 1) there is more muck in the pond
      that he failed to clean out or 2) something else is clouding your
      water like algae. He is right though, plants are always a good thing
      to have in your pond because they process nutrients in your pond and
      if they are the type that root down then they are helping to stabilize
      the mud/muck where they are rooted.

  6. Jean Theron December 14, 2013 at 9:11 am - Reply

    Hi There, i have a Koi pond at my shop but everyday i have to remove the algy from the sides. Its collecting everyday. what would be the causes of this happening everyday and is it safe for the Koi
    Thank you

    • Koi-Care staff December 23, 2013 at 1:55 am - Reply

      Hi, algae won’t grow well without sunlight and nutrients. You may have excess nutrients from your koi pond in the form of uneaten food or nitrogen-based koi waste. There are certain snails you can get to ad to your pond to deal with the algae growth or get a powerful filter to deal with the excess nitrogenous waste.

  7. Dr Gajanan December 16, 2013 at 6:12 am - Reply

    Hi There i Have biught fish tank silver koi. Most of times my koi sits and turns on side at the base of tank . What might be the cause?

    • Koi-Care staff December 23, 2013 at 1:56 am - Reply

      Hi, its sounds like one of two things is going on. Your koi either has some sort of parasitic infection or you have high ammonia from lack of or lacking filtration. I would suggest checking closely to look for visible external parasites as well as testing your water chemistry.

  8. RIDHAA January 13, 2014 at 12:02 pm - Reply

    I have a pond in my yard , i have only recently started paying attention to it since we bought the house ,

    i filled the pond with water and added a dechlorinating liquid to the water .
    after about 2 weeks the water level has dropped tremendously .
    it would be quite expensive to keep addin water and my chlorine levels would be high .

    what could be the cause of this ? and what can i do to save water in ther pond ?

    • Koi-Care staff January 18, 2014 at 1:44 am - Reply

      So I gather you are losing water not just from evaporation but seepage into the ground? Sounds like you may need to install a liner at the bottom of you pond. I don’t know how big your pond is but a liner would stop seepage loss. In terms of chlorinated water from your residential water source there may be in-line chlorine filters that you can install that would effectively deal with the chlorine before the water enters your pond.

  9. john orly March 16, 2014 at 12:12 pm - Reply

    i have a pond in our garden, can i ask when is the time to change the water as it gets dirty? can i change it’s water about 1time a week?

    • Koi-Care staff March 18, 2014 at 12:08 pm - Reply

      Yes you can certainly change water out once a week but I would do something like a 25% change. I’m not sure how big your pond is but of course its always easier to have an multi-faceted filter system.

  10. Joe April 2, 2014 at 2:43 pm - Reply

    I was wondering if you could help me?
    I would like to know when is the best time to open my Koi pond. I live in Louisville Ky. and the temps have been erratic, I usually open my pond around this time of year.
    I usually do a complete water change and clean the pond.
    I keep the pond pump off in the winter but the fish are out and swimming around the water temp. is around 50* .
    I normally put my fish in a small pond while I do the cleanup will this stress them out too much?

    • Koi-Care staff April 3, 2014 at 2:58 pm - Reply

      Its always a good idea to get out a lot of the muck and sludge etc. from your pond but I would recommend waiting a bit longer until the water is at least 55. When fish are coming out of a winter state they are largely running on fat reserves and their immunity to disease may be a bit reduced due to the lack of activity and regular feeding. Moving and handling the fish may cause some stress and that can cause fish with immune systems that aren’t “up to speed” to be more susceptible to disease (such as carp pox which is often associated with a drop in water temps in the fall and increasing temps in the spring). And if you wait until the water is 60 they will be that much more strong in vitality. Good luck!

  11. Paul Harold April 10, 2014 at 3:46 am - Reply

    is “methylene blue” helps for a new home made fish pond, im a newbie in taking care of koi fish 🙂
    or what to do step by step?
    my pond is newly painted about 3 days ago..
    thank you so much

    • Koi-Care staff April 14, 2014 at 6:45 pm - Reply

      Methylene blue’s primary function in the world of fish husbandry is as an antifungal but also will act as an effective antibacterial agent. Hobbyist will use it to treat the protozoan that causes the common fish affliction, Ich. Its also a good substitute for malachite green as its less harsh. It actually has quite a few applications and not just in fish keeping. As for taking care of koi step by step, there’s more to that than I could write in this response but my advice to avoid a lot of potential problems is to 1) keep an eye on your water chemistry and 2) don’t overcrowd your koi pon (less is more)
      good luck, Koi-Care

  12. Joe April 11, 2014 at 10:43 pm - Reply

    Hi, We live in Michigan and this winter killed all of our fish and frogs in the pond. At smoepoint the aerator quit working but I think it would have frozen solid and killed the fish anyway to the terrible cold we had. It was a shame as some of the 15 fish were at least 10 years old and we enjoyed the chirping frogs in the springtime, there were 18 of them dead! We are going to take the opportunity to renew our pond and make it better. Question is what is the best way to clean while retaining the plant life and what equipment would you recommend to replace our already old pump, non0existent filter and a aerator or heater?Thanks for your help!

    • Koi-Care staff April 14, 2014 at 6:49 pm - Reply

      So to clean out the muck without damaging plant life can be as simple as removing the still potted aquatic plants at the bottom of your pond but it sounds like you have established plants so you may want to look into what’s appropriately called the “muck vac”. The vet site ( sells them for less than $100. I think this will be a good solution for you to remove much while not wrecking your established plants but you may want to look into potted plants that sit at the bottom of your pond that remain potted that you can easily remove during cleaning efforts. I have an article here ( about pond plant choices.
      For equipment look into the following:
      Little Giant makes a pump for average sized ponds. It will move around 1900 GPH and that model is called: 566409 WGP-65-PW
      EcoPlus for smaller ponds. This will move around 400 GPH 728310
      Patriot Koi Pond Pump is for larger ponds are will move around 8K GPH
      Tetra Pond has a nice filter called the “Bio-Active Pressure Filter” -I think they come in various sizes.
      Lifeguard Aquatics makes an filter system called the All-In-One Filter and its pretty popular.
      Look at Aquascape or Laguna for aeration.
      Again Laguna for heaters but K&H makes a really good 100 watt heater for koi ponds.
      If the filtration system you choose does not have UV consider an in-line UV. Laguna has an inline system called the Hagen Laguna UV that adds extra sterilizing power.

      Good Luck, Koi-Care

  13. Valarie F April 14, 2014 at 12:24 am - Reply

    Hi I have always wanted to do a koi pond. Right now I have 2 very small Koi in a 30 gallon tank and taking care of them inside the house.
    I am reading this and find It very helpful and will be on here frequently. I live in North Carolina and the weather is humid in the summer and cold winters. We dont freeze or get too much snow where I’m at and when we do it melts quickly.
    Some questions I have:
    How big should the Koi be before putting them in a pond? Nevermind it says when they at mature leel juveniles should be in at least a 29gal tank. 🙂
    So how many inches is maturity? LOL
    How what dimension should the pond be?
    How do I acclimate them from my tank to outdoor pond?
    What plants will be beneficial to the pond?
    I am doing research and reading and learned quite a bit so far.

    • Koi-Care staff April 14, 2014 at 6:53 pm - Reply

      So how many inches is maturity?

      Maturity (at least sexual maturity) is really measured in time so around 2 to 3 years of age is considered “mature”

      How what dimension should the pond be?

      Pond can be whatever dimensions you would like it to be and what your landscape can handle. The size of your pond will dictate the number of fish you pond will have. You wouldn’t want a small pond with a ton of fish in it. You can get pre-fabricated plastic ponds that you just drop into the ground or you can do one in concrete -there’s lots of options.

      How do I acclimate them from my tank to outdoor pond?

      Temperature swings can affect your fish a lot so be sure to acclimate them slowly to any temperature changes. Also you could slowly introduce water from your established pond to your aquarium over days to get them acclimated to that water. I would make sure that the water in your pond you’re going to be building has enough time to establish itself chemically such that your media material has plenty of beneficial bacteria growing on it etc.

      What plants will be beneficial to the pond?

      In terms of plants see my article here:
      Good Luck, Koi-Care

  14. Golden7 April 18, 2014 at 6:42 am - Reply

    I am a beginner level and have 3 kois plus 20 others fishes in a 50gals aquarium tank . Over populated ?Too many?? My desire was to keep the water clear as possible. But the water is really milky .Please help
    Thank you

    • Koi-Care staff April 22, 2014 at 6:38 pm - Reply

      that many fish in so few gallons -I would say you are experiencing some overcrowding. Each one of those fish is producing nitrogenous waste and it looks like your water clarity and quality is reflecting that. Fish, like people, don’t want to be cramped and though it seems like you may get more enjoyment out of having more fish you usually end up with more problems. In the case of having fish as pets “less is more”. You may also want to revisit the power of your filtration system too.
      Good luck, Koi-Care

  15. Janine April 30, 2014 at 1:38 pm - Reply


    I have gold fish and koi in one pond.

    I think my one gold fish has dropsy as it has just gotten so fat or bloated.

    will this affect my other fish and how can I fix it?

    also what is the best way to look after fish in a pond, as it is outside etc…

    and how often do I feed the fish as I was told when I took them over to feed once a week but I see 2-3 times per day?

    I love my fish and want too add more but just im worried as one has disappeared already.

    and I have a filter pump is this sufficient for them?

    many thanks


    • Koi-Care staff May 1, 2014 at 11:59 am - Reply

      Janine, dropsy is an internal bacterial infection or kidney issue/infection and is actually difficult to treat effectively. Its not all that contagious but I would quarantine anyway and add some salt to the quarantine tank for some osmotic relief. Depending on the stage at which your fish is with dropsy you may need to do a series of antibacterial injections.
      So feeding rate of your fish is a loaded question because there are a lot of variables here. What is the season, water temperature, how big are they, how many are there, how much supplemental food is available (i.e. aquatic plants, insects etc.). When you feed floating koi chow you are able to see what is left over at the end of feeding time so you can better judge how much you need to reduce feeding or increase it if nothing is left over. Having leftover food is not going to negatively affect your water chemistry. You want to find that balance. For the most part your feeding rate is largely going to be dictated by water temps. as that is what will affect metabolism the most. I’ve attached a useful feeding guide that I found on -this guide sums it up as well as I could.
      You can add more fish if you want but I wouldn’t over-do it and make it too crowded. Your filter and pump should be sufficient assuming its rated for the size pond that its installed in. If you want to learn more about proper water chemistry, see my article on it here
      Good luck

  16. Karyl Holliday May 2, 2014 at 8:17 pm - Reply

    Hello, I have a koi pond that I’m really getting into. I had a Blue Heron take many of my fish, so now I have been paying extra attention and doing extra research. I have taken care of the bird problem (nonviolently lol) and I really want the new koi to thrive. I also have some commets that had babies last year. How do I best insure that my koi will breed?

    • Koi-Care staff May 6, 2014 at 12:55 am - Reply

      Karyl, on my site there is a new article about koi breeding. Its called “I’ve got koi fry, now what”. If you still have questions after that let me know.

  17. Michael May 3, 2014 at 8:11 am - Reply

    I have a pond which was quiet clear until I 12 Koi. then the water went increasingly green with what I suppose is algae. The pond gets very little sun as it is in our entrance atrium. I have tried all sorts of pond chemicals to help flocculate the water but to no avail

    Please can you help, we haven’t seen the poor fish for weeks now !!!

    • Koi-Care staff May 6, 2014 at 12:54 am - Reply

      Green water which is essentially single celled algae is often associated with spring and summer as that is when ponds begin to experience increases in sunlight and water temps.- both important elements for algal growth. However, another element that aids in algal growth is nutrients such as nitrates. So right off the bat check your water chemistry and make sure you’re not feeding to excess which can result in higher nitrate levels. There are chemicals out there as you’ve discovered that will help to mitigate for green water and those include a products like AlgaeFix and Accu Clear. To really get at the heart of the problem though your water chemistry comes first and after that the next best approach is an in-line UV light as part of your filtration system. UV is a very effective control for algae and doesn’t involve chemicals that have the potential to complicate things.
      Hope this helps

  18. Tricia May 7, 2014 at 3:38 am - Reply

    Hello! I could use some help.. I bought a house that has a fairly large koi pond with koi and gold fish in it.. it is atleast 3 feet deep with gunk. The previous owners couldnt maintain it so now im trying to.. how can I remove the gunk and the koi and clean it out without killing the koi?

    • Koi-Care staff May 8, 2014 at 6:40 pm - Reply

      So to clean out the muck without damaging plant life can be as simple as removing the still potted aquatic plants at the bottom of your pond but it sounds like you have established plants so you may want to look into what’s appropriately called the “muck vac”. The vet site ( sells them for less than $100. I think this will be a good solution for you to remove much while not wrecking your established plants but you may want to look into potted plants that sit at the bottom of your pond that remain potted that you can easily remove during cleaning efforts. I have an article here ( about pond plant choices.
      By the way, 4 feet is really a better depth for your pond if you can achieve it.
      good luck

  19. Joey ceselka June 9, 2014 at 11:16 pm - Reply

    Hey, I have a fairly large butterfly koi and 3 smaller koi I have a pond but I didn’t put them in it yet I currently have them in a 50 gallon tank, the big koi I had for about a year and it’s fine but the 3 that I just bout don’t swim that much they eat and they’ll swim a little but they mostly stay in one spot what should I do ?

    • Koi-Care staff June 15, 2014 at 1:30 am - Reply

      Well 50 gallons isn’t that much space for 4 koi so that may be a factor in why they are not moving or you may have gotten koi with some health problems. I would put your big koi in when your pond is ready and then do the small ones one at a time so you can determine if changing their habitat affects their behavior. Have you taken steps to make sure that the 50 gallon tank has plenty of aeration and filtration? With four fish and a small space waste can build up quick and oxygen can get depleted.

  20. christal June 26, 2014 at 10:02 am - Reply

    We have a 26000 gallon pool 30′ ×15′ and 3-6feet derp…. that we converted into a gold fish pond. I can’t seem to find large enough volumes of algefix type products to get the water clear any more than 1 foot deep…so lower 3-5 feet is totally green. Also having trouble finding a filter uv or carbon that can cycle at this high volume. Fish seem very happy…and reproduce like crazy. Direct sunlight and only small fountain for air circulation at this time. Will barley really help with the nutrients. What can I use to eat up the sludge…
    refer nstural over chemicals. Again finding products in volumes high enough for 26K gallons proves difficult.

    • Koi-Care staff June 30, 2014 at 5:51 pm - Reply

      Hi, I have a swimming pool that is 30 by 15 with a depth range of 3-5 feet and its about 14k gallons -if your pond was 30 x 15 x 6 all the way across it would be 2700 cubic feet or just over 20K gallons -I’m thinking that your pond is actually under 20K gallons. This is obviously important to be as close as possible to the actual volume for the purpose of adding chemicals etc.
      Not all algae is bad. For example, string algae is actually not that bad for your pond- the fish eat it and it produces oxygen. Of course it looks bad and will suck up oxygen when it dies and decays but other types of algae are normal to have in your pond and won’t cause problems. My guess is that this algae that is in the lower 3-5 feet is a carpet-like algae and is under 2 inches in length. You will want to keep that stuff around. Its typically 1/4 of an inch to 2 inches and under normal conditions will cover everything. As you have found out algecides won’t do too much to it -thats fine, it won’t hurt your pond to have that algae. It sounds like your pond it doing well and your fish are happy and that’s all you can ask for.

  21. Al Motta July 9, 2014 at 3:11 pm - Reply

    We’ve got an 80 gallon outdoor pond – an old molasses boiler.
    In it, we’ve had (5) 5″ goldfish and (1) 12″ long approx. 3 pound koi.

    Is the pond large enough?

    We keep the water moving through a basic filter, replace the water with city water when it evaporates and occasionally add algae reducer. The fish all appear fine


    • Koi-Care staff July 22, 2014 at 2:58 pm - Reply

      hmm, sounds small to me but as long as you have the filtration and water movement you should be fine (and it sounds like your fish are doing okay). I don’t think I would add any more though.

  22. Laura July 15, 2014 at 3:10 am - Reply

    I am purchasing a home with a koi pond. The Lilly pads have taken over the surface. Can I just pull some out? I have no idea how to care for this pond, but I know I will love it.


    • Koi-Care staff July 22, 2014 at 2:53 pm - Reply

      you can pull them out if you wish but lillies are good for your pond and fish. They provide shade and cover for smaller koi. My recommendation would be to have at least 60-70% surface coverage for your pond. Obviously you will want to see your koi but you need to find that happy medium between your enjoyment of your koi and their well-being.
      Good luck and if have any issues come up there are plenty of resources on my site as well as a pretty comprehensive PDF guide.

  23. Bev Sikes July 23, 2014 at 3:30 pm - Reply

    We inherited a small (40 gal outdoor) Koi pond with filter system when we moved here in May. No problems until recently. We have 3 2-3″ and 3 3-4″ koi. Our ammonina % was VERY high. We did a 20% water change twice. We’ve added ‘Ammo-loc’ and its still very cloudy. How long does it take to clear…and directions say to repeat w/’ammo-loc’ every 2 days.
    We had water checked and all was good except for HIGH ammonia. We have cleaned our filter and will do so every 2 weeks. We do have plants in our pool. The algae is slimy and covers everything. We’ve cleaned it off with brush and water only. This is also a new development. Would snails help?
    Need advise on clearing up water, slime, maintaining low ammonia %, etc
    2 wks ago we could see clearly and enjoy our Koi. Not now.
    Thank you for any advise you can give us.

    • Koi-Care staff August 5, 2014 at 6:23 pm - Reply

      hi, so first off if i remember correctly about ammo-loc and similar products they may be sequestering the ammonia but your tests will still show it so you may be getting a false positive. Having said that however you may actually have high ammonia due to a small volume of water and a good number of fish. This pond may be have been humming along fine for the last year or so however fish tend to grow faster in the summer and a 40 gallon pond that supported 6 fish before when they were smaller may not keep up when the fish get bigger -its not a static system. 20% water changes are good but watch for pH swings and you should continue to do the water changes. The other thing I would recommend is boosting your beneficial bacteria colonies on your filter media -this will help to assimilate the ammonia, nitrites, nitrates etc. You’re seeing excessive algae because 1) its summer which means more sunlight and longer days and 2) there’s plenty of nutrients (ammonia). So in the short term i recommed (besides water changes and boosting your bacterial colonies with something like “microbe-lift”) is koi clay. You can read all about free floating and string algae in my most recent article here ( In that article i talk about the benefits of koi clay.
      The other thing I would consider for a future addition to your filtration system is a UV sterilizer -kills microbes, bacteria, viruses, free floating algae -great addition to your pond.
      Lastly I would also be concientious of how much food you are putting in the pond. If you use floating food you can more easily see how much they are not eating and feed accordingly next time.
      Good luck, Grant

  24. Dodie Bruening August 1, 2014 at 7:56 pm - Reply

    I need to remove my 12 6-12″ Koi from the lined pond which holds 1500-2000 gals.and clean years of accumilated sludge, and build up on sides and bottom-my concern is I have purchased a 100 gal. rubbermade structural resin tub to keep my Koi in while I do this clean up I will use a pump to ariate and keep the water moving and wonder if my Koi will be okay if this job takes more than a few hours to complete-thank you for any help/advice you can give

    • Koi-Care staff August 5, 2014 at 6:19 pm - Reply

      I think you should be okay with that size container- though it sounds like it will be tight.

      • Dodie Bruening August 6, 2014 at 3:14 pm - Reply

        Yesterday, 8/5/14 I cleaned the pond, filters and pumps,the fish did great but overnight the water has turned very cloudy–please, have you any suugstions as to what caused this and what I can do to clear up the cloudiness, and prevent this from happening again–thank you

  25. sandy.gill August 4, 2014 at 4:29 pm - Reply

    I have 18 and they are multiplying like rabbits any one that wants some let me know.i rescued them a year ago and they are very nice colors.their starting to pick on each other due to the fact i have to many in a 135 gallon pond..lots of babys multi colors.please help.

  26. Dodie Bruening August 6, 2014 at 3:25 pm - Reply

    This may be a double post because I did post a reply about my pond clean up–but want to be sure you get it so here goes, Yesterday 8/5/14 I cleand the pond, filters and pumps–the Koi did great and looked beautiful in the clear water but over night the water has turned very cloudy, can you offer any suggestions on how I can clear up the cloudiness and how to prevent it from happening again, thank you

  27. Jo France August 31, 2014 at 6:22 pm - Reply

    We have a 800 gallon koi pond.we use an aerator 24/7 also use Algae buster once a month. Have floating plants for shade.we had 3 koi to die in the last two weeks. They look healthy feed once a day. What are we doing wrong?

    • Koi-Care staff September 15, 2014 at 3:34 pm - Reply

      Well, it could really be a lot of different things that could explain these sudden deaths. What is your water chemistry like? Is there anything out of balance? You could very well have had parasites get your fish and you won’t know until you start looking at some skin samples under microscope. What kind of temperatures is your pond reaching? Plant shade is good but 800gal is on the smaller side and may be heating up pretty quick. Stress can often lead to eventual koi death. For example you may have raccoons or wading birds going after your fish when you’re not at home and causing stress (and therefore compromising the fish’s health). What about the water coming into your pond? Is it chlorinated city water? Has there been a lot of rain and runoff bringing something undesirable into your pond like fertilizer or weed killer chemical from a nearby lawn?
      When it comes to koi health, issues usually can be traced to water quality. Poor water quality by itself can lead to direct koi death as well as indirectly by allowing parasites to flourish and infect your fish. So that is where I would start if I was experiencing your situation. I hope this helps.

  28. Jessica DuFeu October 7, 2014 at 9:29 pm - Reply

    First of all I live in Montana so we all know that the winter’s are very cold here. I usually bring my fish in during the winter months and have them in 150 gallon tank. But this year my goldfish had babies and one of my koi’s got super big. I was thinking of leaving them in the pond with a tank heater. But don’t wanna lose my big koi. What temperature does their water need to be for them to be safe through the winter??

    • Koi-Care staff November 4, 2014 at 4:17 pm - Reply

      Hi, the typical practice for overwintering koi is to put an aerator at the bottom of the pond and let nature do its thing. Ice will form over the pond and they will go into a slower state with severely decreased metabolisms. Lots of fish species overwinter under ice and that includes koi. If you are uneasy about the pond icing over some people will do floating de-icers but when a pond ices over it kind of buffers the pond inhabitants from the elements of winter.

  29. Paul Carline October 9, 2014 at 12:28 pm - Reply


    I have a new Koi Pond approx 9000ltrs.All going well except pond is only clear for approx first 6ins.It does not seem to be Algae more a brown colour.The pond was running on an inneficient system for 4 months.System now changed to include 40w U.V.

    Tried loads of treatment but am now thinking I have been purchasing Algae removal when perhaps I should have purchased Sludge Remover.

    Any advice would be very much appreciated.



    • Koi-Care staff November 4, 2014 at 3:57 pm - Reply

      Paul, it sounds like you may have some much/sludge at the bottom of your pond that is getting stirred up and staying stirred up due to fish or water flow. You could look into pond vacuums -they range in price and power but that may do the trick. If its brown its unlikely to be the free floating green algae that causes “green water” for which your UV would work great on. I wouldn’t recommend getting rid of the UV though because its so useful in killing microbes. The other thing you could try first (and wouldn’t be too expensive) is something called “koj clay” (you can read more about it in my algae article on my site Its meant to kind of grab any flocculent in the water and take it down to the bottom (and subsequently koi love it for some reason).

  30. Jen January 20, 2015 at 6:38 pm - Reply


    For the first time we have fry 🙂 (separated from the big pond into two smaller ponds) – they are 5mm in size – feeding them finely crushed koi food twice a day however both the ponds have become so cloudy – how do I clean without injuring the fry?

    • Koi-Care staff February 8, 2015 at 3:29 am - Reply

      I don’t know how you have your ponds set up in terms of filtration and how close to each other they are but what people will often do to avoid fry getting caught up in the in-take is to use a sponge pre filter. You’re going to get cloudy water with uneaten food and a lot of bio-activity taking place. You may want to think about doing a cull, too.

  31. Bruce Dixon January 27, 2015 at 5:32 am - Reply

    Is using a Pond Dye also suited for pond maintenance? I mean, many people on the internet say that using pond dye on your pond can also help prevent the growth of algae on the pond (as this the common problem when it comes to pond) please do let me know. Thank you!

    • Koi-Care staff February 8, 2015 at 3:27 am - Reply

      I can’t comment on that particular brand of dye but yes, dye is an effective way of reducing light into your pond (and therefore algae). I cover a lot of algae reducing techniques in this article too.

  32. Kimi February 8, 2015 at 2:47 pm - Reply

    I am new to my koi pond. It came with a home I purchased. My pump motors are enclosed in a black box. When I clean out the pump boxes, there are always these little ameba looking jellies on the box. What are they and how do I stop them from forming? Also, all of my water Lillie’s have died…is this something that happens seasonally when it gets cold and will they come back when it warms up? Thank you for any help/info you can provide.

    • Koi-Care staff February 17, 2015 at 7:56 pm - Reply

      The jelly things? It may be slime mold but its hard to say. Is it clear? how big is each one?
      As for the Water Lily, there are many diff. kinds to include those that are more tropical and those that are more frost tolerant. My guess is that the previous owner bought the plants locally and installed them which suggests that the seller is most likely carrying the appropriate, hardy Lily type.

  33. Heidi March 4, 2015 at 3:16 am - Reply

    Hi. We have a 65 gallon aquarium with two 12 inch koi and it is overcrowded, too much ammonia despite our new high quality rated 150 gallon canister filter they developed ick this week when I stopped changing 50% of their water every other day. We are having a custom 200 gallon aquarium made for us this week with an overflow and sump filtration and a uv filter. Will this be enough for them to thrive and we were considering adding one more koi. Would that be ok? Do we need a protein skimmer? Thank you.

    • Koi-Care staff March 9, 2015 at 3:33 pm - Reply

      hi, I’m more familiar with koi filtration systems for ponds but I have spent enough time in State aquariums husbandry dept. to say that protein skimmers are a good idea. As for the 3rd koi -you may want to let everything settle out first and see how your new set up works out (water chemistry-wise) before adding more fish. One thing you may want to keep in mind when doing pretty substantial water changes is that you run the risk of large pH swings which isn’t great for your koi. I understand you were doing it to knock down the ammonia but its worth mentioning. As a side note, you may want to give your new aquarium some time for the silicone (if used) to outgas before adding water-that typically takes about 24 hours.

      • Evans April 6, 2015 at 12:46 am - Reply

        Hello there i live in the eastern part of Greece in an island and I just made my first pond. I have many years an aquarium and iam really exp. of keeping fish. My pond measurements: length 2.80m x width 0.80m for 1.70m of the length and the rest width is circular pond 1.20m width. the depth o my pond is approx. 30 35 & 40 the deepest. I have 4 small koi and 3 small gold fish so far I would like to know (as i have read many articles about koi)if i can keep the fish in that pond and also is that true that the fish usually they grow depends of the size of their environment ? also the greek environment for the depth of my pond is it ok ? Thank you !!!

        • Koi-Care staff April 11, 2015 at 2:45 am - Reply

          some of your message didn’t come through quite right so I will try to answer the best I can. As far as the number of fish you want to have in your tank you can figure on 33.33 gallons of water per inch of koi or 126 liters of water per 2.54cm of fish. So its not so much about the number of fish but rather the size as the size will dictate the amount of demand on the filter. Fish will outgrow the size of their environment. As far as the depth is concerned, 2 feet (61cm) is alright, 3 feet (91cm) is better and 4 feet (123 cm) is great.

          μερικές από τις μήνυμά σας δεν έρθει μέσα από απόλυτο δίκιο γι ‘αυτό θα προσπαθήσω να απαντήσω όσο καλύτερα μπορώ. Όσον αφορά τον αριθμό των ψαριών που θέλετε να έχετε στο ενυδρείο σας, μπορείτε να υπολογίσετε σε 33,33 λίτρα νερού ανά ίντσα koi ή 126 λίτρα νερού ανά 2,54 εκατοστά των ψαριών. Έτσι, δεν του τόσο για τον αριθμό των ψαριών, αλλά μάλλον το μέγεθος και το μέγεθος θα υπαγορεύσει την ποσότητα της ζήτησης για το φίλτρο. Τα ψάρια θα ξεπεράσει το μέγεθος του περιβάλλοντός τους. Όσον αφορά το βάθος, 2 πόδια (61 εκατοστά) είναι εντάξει, 3 πόδια (91 εκατοστά) είναι καλύτερη και 4 πόδια (123 cm) είναι μεγάλη.

  34. William March 15, 2015 at 3:56 pm - Reply

    Can termite problems be solved? If a pond liner or return lines have developed leaks due to termite problems, would it make sense to renovate the pond and install a new liner and return lines? Or is it that once you have termites you will always have termites so that it would only be a matter of time before the new liner and lines started leaking?

    • Koi-Care staff April 11, 2015 at 2:53 am - Reply

      Termite issues with a koi pond is a new one on me! I am more familiar with the damage that wood destroying termites do as opposed to ground nesting termites. I do know that ground nesting termites act much faster than their woody cousins. I ‘d hate to see you re-do everything. Is there a way you can have them treated on a regular basis then once you’re confident that you have them under control go in and fix leaks?

  35. Tony March 17, 2015 at 1:31 am - Reply

    If the Alga drys out before I refill the pond what steps do I take when putting the koi back?

    I set up a 250 gallon temporary pond with water from the larger pond and then transferred the Koi. the Temperature in both the pond and temp tank was 75 degrees
    The existing pond has rubber liner that was installed 18 years ago and still look good and playable.
    There is a very dark green alga about 1/4 long growing on the sides and bottom which the koi nubble on between feedings. After the water was removed the alga tuned light green.

    Since I drained the pond out completely I am afraid the alga will die what steps should I take to clean the pond before putting the Koi back?

    • Koi-Care staff April 11, 2015 at 2:52 am - Reply

      You could spend some time and effort scrubbing the liner with a plastic bristle brush (similar to those you see used on pools) but a lot of benthic algae can survive being dried out. They can be dessicated for years and come back after rehydration.

  36. Maria March 21, 2015 at 4:32 pm - Reply

    Hello my father is building an extremely large Koi Pond (looks like a lake to me) in the center there will be a cascading water fall as well as on one of the edges too. After measuring and using a pond calculator it claims the volume will be 180,000 gallons of water. the entire pond will be 4ft deep he is very knowledgeable when it comes to building ponds , cascades, waterfalls and fountains. But we are clueless with Koi and Natural Plant life for this pond. What do you recommend as to the proper # of koi for this pond? The lowest temperature where we live during the winter is 38-40 degrees will we need heaters? What plant life do you recommend? Thank you for any information you can help me with, as I want to educate myself before we take on the venture of purchasing the fish.

    • Koi-Care staff April 11, 2015 at 2:50 am - Reply

      one of the purposes of my site is to sort of start from the beginning with topics and not make certain assumptions of prior pond or fish knowledge so I would say start with my article on koi pond plants but you should also expand too and read other sites to get maybe a different perspective or approach on it. One thing though is that you probably won’t be able to achieve much tree shade with that much surface area so you will def. want to have plenty of surface coverage via plants to provide shade -thats important. That is covered in my article on pond plants. 4 feet deep is a good choice. You don’t need heaters (that would cost more than a mortgage in heating bills for that kind of volume!) and it sounds like you don’t get iced over ponds either which means you can enjoy your fish year round. They can handle low temps. -they can survive iced over ponds for an entire winter so 38 degrees is not a problem. Appropriate number of fish for this pond? thats a big question because there are a few factors to consider. How much maintenance do you want to put into this thing? if your fish get sick fish and its contagious you need to think about the effort of treating all these and not to mention feeding all these fish. If you stock to maximum carrying capacity of the water volume you need to consider that they will grow and they will produce, both of which mean more demands put on your system and your filtration etc. My personal opinion on stocking is that less is more. Are pond owners more pleased with 48 fish vs. 36 fish swirling about at feeding time? Probably not. I subscribe to the notion of “the law of diminishing returns”. So how many is enough? That is really up to you…mostly. Obviously there is a limit to what you want to stuff into this pond and the problem is that you ask 10 experts on koi pond and you will get 15 different ideas on what that capacity really is. Some say 33 gallons per inch of koi, some say 10 gallons per inch of koi, some say one koi per 250-300 gallons. Most owners never really have to face a situation where their pond is just busting at the seams anyway. So you father’s pond could sustain quite a number of fish but realistically you may limit yourself to 75 or 100. There is a good book that I recommend on my site that goes through everything from start to finish -its only like 20 bucks and has a lot of useful info. (and if you don’t like it you can get a refund). Good luck and when you get this thing up and running set some pics, I want to do a sort of “bragging board” page on my site soon.

  37. Elizabeth Mbizvo March 23, 2015 at 5:48 pm - Reply

    Hi, I have had a koi pond for 1and half years. I started the pond using water from a bore hole. We were purchasing the water in bulk for home use as well as using in the pond. Recently we started getting municipal chlorinated water. My house help today topped up the pond with the chlorinated almost 1000Ls in a pond that takes 4000L of water. I am very worried. Will my koi fish die. What immediate measures can I take to save my fish. They are of different age groups. 4 are 1.5 years old, and about 20 are around 6 months old.

    • Koi-Care staff April 11, 2015 at 2:47 am - Reply

      Right, you def. want to treat the tap water first if it is coming from a municipal souce. You could add something like TetraPond Aqua Safe water conditioner or Amquel by Kordon.

  38. Coachmartin April 8, 2015 at 1:34 am - Reply

    Hi all I have 150 gallon koi pond and I want to change the water I have a few goldfish as well one has died but the other 8 or 9 goldfish are still alive..I have three koi fish and they are going really strong I have had the pond for about a month and a half and I don’t want any others to die all my hard work to go to waste. What is the best way to add water to the pond and allow the fish to adjust to the new water.

    • Koi-Care staff April 11, 2015 at 2:44 am - Reply

      Hi, you can do something around a 20 percent water change then after things settle test the water chemistry paying especially close attention to pH swings – big changes in pH will be problematic for your fish. A be sure you’re not putting municipal water in as there is often some chlorine in it.

  39. Sarah April 16, 2015 at 3:20 am - Reply

    We’re in the process of purchasing a house that has a relatively small koi pond. While the fish are lovely, I’m not sure I’m up for the commitment of properly caring for the fish. Do you have any recommendations for how I can go about finding them a new home?

    • Koi-Care staff April 20, 2015 at 7:42 pm - Reply

      Susan, sorry I must have missed your email. So for getting rid of your koi: look up online for some local koi keeper clubs, put up a flyer at a local seed and feed type place letting people know you have fish to get rid of, craigslist, possibly a local pet store will take them but if not they would have some good ideas, usually people that have horses and land for these horses will also have fish ponds so track down some horse people! Koi forums are also a good place to tell the world you have koi to give away.
      Good luck, grant

  40. Hieu April 20, 2015 at 12:59 am - Reply

    It’s Spring and the weather starts to warm up. First, when it was around high 40/low 50, some of the koi were laying sideway flat on the bottom. I took those 3 out and put them in a 200 gallon tub at .5% salt water. Immediately after I put them in, they stopped laying on the side, although they seemed to be very nervous, darting across the tub. After one week, they calmed down, so I put all of them back in the pond.
    However, I also took an Utzuri to the tub because I noticed the white part has taken on a pinky color. After one week in the tub, he did not seem to be better, and did not eat much, so I put him back in the pond too. He seems to be happier and fight for food again. One big white koi I saved from a huge ulcer last year, also has that old ulcer area looking a bit pink. I am trying to look at the other koi, but there was no clear sign of their skin turned pink.
    A have about 30 koi, and the last 2 days I’ve seen 3 or 4 of them jumped up.
    I checked the water and everything seem to be OK, but I am worrying that the test I use would not show parasites or some other issues than ammonia, nitrate, phosphate, or ph.
    May I ask if someone can tell me if there is anything I should do, or just wait for them to get over?

    • Koi-Care staff April 20, 2015 at 7:41 pm - Reply

      For the most part, if your water chemistry is within acceptable ranges then you really shouldn’t have a big issue with parasites but as it is spring it can certainly happen. you could do salt in your main pond as well as a boost to your filter media via something like Microbe Lift PL. a lot of the times koi look to be a bit off in spring because they are still coming out of their winter state of dormancy.

  41. Ryan Morrison April 20, 2015 at 1:38 am - Reply

    I have a huge fish pond at a new house I just bought… Approximately 4 feet deep, 6 feet wide and 12 feet wide… Bi-law officers just told me my depth of pond can not exceed 1. 5 feet (it’s currently 3.5) ffeet deep… Can koi fish survive in that shallow of depth, what’s the best way to raise the pond from 3.5 to 1.5 feet.. I have about 30 fish and would hate to lose them, what are my options?

    • Koi-Care staff April 20, 2015 at 7:40 pm - Reply

      Interesting problem. Can they survive in that depth? Well, it depends on whether or not you live in a cold environment that experiences freezing ponds, depends on the size of your fish (smaller will do better with less space than large ones). If you were going to build a koi pond tomorrow, that wouldn’t be the depth you would make it so maybe the solution right now is to keep just the smaller ones. As far as filling in the 2 feet of depth I’m not sure -maybe bring in crushed rock fill?

  42. Chen April 25, 2015 at 6:58 am - Reply

    I live in Southern California.I always want to have a koi pond in my back yard.
    But after I read all above information. I have some questions.
    1) will summer time be too hot for Koi in Southern California?
    2)How big size and how deep will you suggest to build new Koi Pond?
    For koi lover I need lots information and suggestions to build new pond.

    • Koi-Care staff May 1, 2015 at 2:07 pm - Reply

      S. California won’t be too hot and what you do to offset hot conditions is to make your pond deeper-say 4 feet. It tends to be cooler at the bottom in the summer. As far as the size of your pond that Will depend on the space you have available. Some a just a couple hundred gallons, some are several thousand gallons. If you want to get a good introduction to Koi and pond building there is an eBook that I recommend on my site – its only 20 bucks and if its not helpful you can get a refund. The other big question for you is going to be: how do you build a koi pond with california’s new water restrictions?

  43. Kyle May 3, 2015 at 10:04 pm - Reply

    Hello. I have read through some comments n understand what too do as I have had couple freshwater tanks n salt in my house before. But just bought eh home with a 35 ft long pond. One side is 6 ft deep, n other 4 ft n hf . Now there is a center water fall that seems too feed a river system for the ponds, there are many kinds of water plants that have started too grow but what steps do I take for clean as winter just ended n the past owners have stripped the plumping, filter system , n protein system, I would love too save the plants n have the water back before starting to intuduce the new fish. Past amount of koi was 30 plus fish. Please help.

    • Koi-Care staff December 1, 2015 at 3:00 am - Reply

      there are all-in-one systems (which may not be appropriate for larger ponds like yours). Personally, i like the Performance Pro pumps-they have both submerged and external pumps.

  44. alec m morris May 4, 2015 at 3:23 pm - Reply

    hi,I have a large pond in my large back garden,i have a good selection of koi carp common carp, gold fish shabunkins etc.Some of these carp i have had for over 16 years without any problems but this year they are not eating yet.The water was looking brownish so i have changed the filters which has improved it a bit, i have a skimmer which keeps the top of the water clean and a uv light that keeps the water clear of algae. I also have some large albino grass carp who control the duckweed.can you please make any suggestions why my fish are not eating.My pond has been netted so i do not have any problems with heron etc.

    • Koi-Care staff May 7, 2015 at 6:54 pm - Reply

      sounds like everything is fine but as you know when they come out of their winter dormancy they are not going to have ramped up metabolism yet. What is your water temp.? The water temp. is really going to be the biggest factor in getting them up to speed in eating. I’m sure of your location but if you are in the more extreme northern latitudes you could have water that is still fairly chilly. Are you certain that they are not eating other plants or insects?

  45. Rachael Snaith May 15, 2015 at 9:36 am - Reply


    We had a heron and some of our gold fish died from injury / post trauma infection but now some of the goldfish seem to die for no reason. i have treated the water with medifin, fed them medi-loi but they seem to still die possibly one or two a week including a baby goldfish this week. distressing…

    the koi have all been totally fine.

    what would cause this?

    • Koi-Care staff December 1, 2015 at 3:00 am - Reply

      The mortalities could have lot of explanations but usually the culprit is water quality. How do your dead fish look? Red streaks? Ragged fins? Other indicators of cause? You my very well have a dead fish at the bottom of your pond decaying and increasing ammonia and nitrites

  46. Janice Lenzer June 5, 2015 at 3:38 am - Reply

    I am new to koi and also have comets in my pond, 350-400 gallons. I did have 2 red and white comets fairy large and one smaller, we adopted 4 koi about 5-8 inches and I havd about 40 feeder fish and a calico rhyskin. Something happended and the ter was high in ammonia as ell as pH which I know makes athe ammonia more toxic. Many of my fiah died and this is how I discovered the water level problems. I changed much of the water a little at a time as there were a few remaining fish. I was devastated but think the pond is back on track and want toget more fish. Yet the ammonia lvel is still a little high at .25 and some are saying it will remain that way even with the ammo – lock chips I put in to clear it because it just deactivated ath ammonia not rids the pond of it. Is it safe to put other fish in? how will I know if the treatment chips will give a false reading as I have read about?


    • Koi-Care staff June 20, 2015 at 2:29 am - Reply

      Janice, sorry about the delay but yes, ammo-lock type products are sort of misleading so the best advice i would have for you is to do several water changes and increase your beneficial bacteria load on your filter media. both of those actions should result in an ammonia reduction which is important because high ammonia is so harmful to your fish.

  47. jenn June 6, 2015 at 12:03 am - Reply

    What would be the best way to clean the pond liner when you look in to the pond all you see is the bottom and sides that look like dirt how do I do it with out making my pond look like a mud hole and safe way for my koi fish

    • Koi-Care staff June 20, 2015 at 2:28 am - Reply

      People will typically remove their fish and hold them in a temporary pen until the cleaning is complete and your water chemistry looks good.

  48. Dee June 16, 2015 at 8:23 pm - Reply


    I bought a house a year ago and I have 2 ponds one feed into another. One pond have 8 medium size and one have 5 large size koi. Last week on the top pond, one medium size died when I was traveling and the fish sitter took it out and buried it. Last few days since, the fishes are on the bottom and wont eat. Today I found 2 dead mini frog in the filter. I called the pond guy to get him to come clean the pond, meanwhile any advise? Its been very hot around 97-98 here.


    • Koi-Care staff June 20, 2015 at 2:22 am - Reply

      If your ponds are shallow enough you could be getting elevated temps and therefore reduced dissolved oxygen. They may also be seeking cooler water down deeper. Have you checked your water chemistry?

  49. Patty July 2, 2015 at 3:09 am - Reply

    Hi, I just had a 55 gallon pond built in my backyard. We put 8 Koi fish it 4 days later the fish were laid eggs my pond is now dark green is that normal?

    • Koi-Care staff July 13, 2015 at 3:19 pm - Reply

      Are you saying that only after 4 days you already had eggs laid in your pond from the koi? It is unlikely that it would happen that fast due to the fact that they are still getting used to their surroundings and probably suffered some amount of stress from being introduced to a new environment. Are you sure they aren’t frog eggs. Turning green sounds like green water algae (free floating algae). See my article on algae -I think it will be of some use to you (

  50. Travis July 9, 2015 at 9:56 pm - Reply

    We recently bought a house that has a Koi pond with 4 Koi ranging from 8 to 24 inches. It has a 30 foot water fall feature. I dont want to run the waterfall all the time because of the cost of electricity. The pond is about 1300 gallons. I purchased a water feature pump that does 285 gph and splashes back on top of the water to put oxygen back in the water. Would that be ok to run that for about 10 hrs a day and then use my pump that runs through the filter and waterfall for the rest of the time? I just want to make sure the fish are getting enough oxygen.

    • Koi-Care staff July 13, 2015 at 3:11 pm - Reply

      Yes, I think your solution to provide dissolved oxygen while saving on some electrical costs will be fine.

  51. sharleen July 13, 2015 at 9:02 am - Reply

    Hi there I live in South Africa and I find this website very in formative and I purchased 2 baby koi yesterday and have it in a circular tank my concern is if they will be able to survive in it without a pump or filter. I heard about some oxygen tablets would that be a better idea to put in the water once a week. Please any help would be appreciated. Thank you kind regards Sharleen

    • Koi-Care staff July 13, 2015 at 3:09 pm - Reply

      Sharleen, there is a certain amount of gas exchange that occurs at the surface of the water naturally and the addition of the tablets will help but its not a permanent solution -you will need a pump and filter for long term survival of the fish. Without filtration, their excrement etc. will cause a build up of ammonia, nitrite and nitrates which will cause the demise of your fish.
      Good luck, Grant

  52. joie July 25, 2015 at 1:25 am - Reply

    hi there….im just curious about my small koi..because it is swimming like something is stuck in its throat and wriggling movement.. i check it out the throat but nothing there,,,,its been a 5 days now and another one of my small koi get the same symtoms….could it be an parasite?

    • Koi-Care staff July 29, 2015 at 5:51 pm - Reply

      certainly, koi can get parasites in their mouths

      • joie July 31, 2015 at 1:02 pm - Reply

        hi there … i just separate my two small koi into a aquarantine tank,,,i try to feed them small amount of food everyday,,,they eat normally but,,,their movements are not the same as before they are swimming diffirently…when they swim their body is shaking that is like something stock in their mouth,,,ths my first time seeing ths kind of disorder in my kois.. im keeping an eye on them everyday,,, how do i share a video here? so you can see..

  53. Deb Schaffer August 11, 2015 at 9:52 pm - Reply

    I have 4 large koi in a 1000 gallon pond. We put this pond in 10 plus years ago and now we would like to redo it. Over the year the rocks we put to hide the liner have shifted and moved and the koi have grown to an extra large size and could use more room. My question is….how do we move them into a horse watering tank for a week or so while we completely redo our current pond. We’d like to put in a purchased biofalls and skimmer box. What do you recommend? Originally my husband built a bio falls and skimmer box out of rubber maid containers which have worked well but we’d like something better for our fish going towards our old age. We know the rubber maid will not last forever. I’m worried for my fish moving them out of their environment even for a short time. Suggestions?

    • Koi-Care staff August 30, 2015 at 1:15 am - Reply

      As long you get a large enough net and do it pretty quick they should be fine -those guys that bring their prize fish to shows are always moving their fish around. As far as biofalls go I like Aquascapes Microfall Filter -its rota-molded (vs. weaker injection molding and I believe they have a lifetime warranty. Good luck

  54. ardee un August 18, 2015 at 1:40 pm - Reply

    can Koi fish survive without aeration? or air pump in pond?

    • Koi-Care staff August 30, 2015 at 1:13 am - Reply

      Yes…and no. If all other things are equal they would most likely be fine but the elements that can cause low dissolved oxygen is stagnant water that is shallow with an abundance of koi. There will be natural gas exchange at the surface of the pond but if there isn’t much water movement you won’t have that dissolved oxygen distributed throughout. If the pond is shallow and its middle of summer, warm water doesn’t hold as much dissolved oxygen as colder water so even in the natural environment there can be fish die offs due to insufficient dissolved oxygen so it can certainly happen in a koi pond. It just helps to have some extra aeration in the pond -the fish will be more active and happier.

  55. Mike Natkaniec August 25, 2015 at 7:52 am - Reply

    i have had some Koi for several years, recently several of the larger fish have started to float on their sides as if they are dead. When they are touched they swim off and swim around, after a while they go back on their sides.

    • Koi-Care staff August 30, 2015 at 1:11 am - Reply

      It could be one of a few things going on. You may have an swim bladder infection (or otherwise not functioning properly) such that the fish cannot inflate/deflate the swim bladder properly. There may be some compacted food in its digestive system and may need only feed to feed the fish some frozen peas. It may also be some kind of internal infection.

  56. Tony Pulis August 31, 2015 at 8:44 am - Reply

    Can you please tell me if koi and goldfish can inter-breed when they are mixed in the same pond?

    • Koi-Care staff October 9, 2015 at 3:36 pm - Reply

      I’ve never heard any stories of them interbreeding. Koi and carp are Cyprinus carpio while goldfish are Carrasius auratus. They should not be able to produce any viable offspring.

  57. Courtney October 5, 2015 at 3:26 pm - Reply

    We recently purchased a home with a Koi pond and indoor pond for the Koi to winter. We emptied out the indoor pond during this summers months and are now ready to transfer them back into the house. We would like advise on what to clean the tank with, how long we leave the water sit before transferring(we are on non chlorinated well water), and what types of chemicals do we need to add to this tank. As well we have lights on timers and a pump with a filter, should we add anything else?
    Another concern we have is the pond outside . Do we clean it pre winter and then on spring or just leave it?

    • Koi-Care staff October 9, 2015 at 3:25 pm - Reply

      If your indoor tank has been empty, what is making it dirty? Is it just dust etc.? So once you have refilled this indoor tank the most important thing is to make sure your water chemistry looks right and one of the ways you do that is by initiating the beneficial bacterial colonies on your filter media. For example Microbe-Lift PL ( is a crowd favorite. Another thing you can do is get some gold fish and stick them in there to get some biological activity going. You shouldn’t really have to add any chemicals especially if you don’t have chlorinated water of any kind. Outdoor pond cleaning typically happens in spring. Another option is to skip the whole thing and leave your koi in the outdoor pond throughout the winter (assuming its deep enough and you have a floating de-icer).

  58. Barbara Anders October 25, 2015 at 3:39 pm - Reply

    Hi, we just yesterday had our pond cleaned and I have a question. We have goldfish in it, it’s about 100 gallons, and the guy really cleaned it well–to the point that there’s NO algae left. We’re in South Central Virginia. We typically stop feeding around October 1 and know that they hibernate over the Winter but there is nothing for them to eat now. My question is will the fish need any kind of feeding at this point, or is there anything we should do?

    Thanks for any help!

    • Barbara Anders October 27, 2015 at 3:41 pm - Reply

      Thanks so much!

    • Koi-Care staff December 1, 2015 at 3:09 am - Reply

      your fish should be fine. when the water gets cold, their metabolism slows way down and processing food material becomes very difficult anyway.

  59. Kelly November 14, 2015 at 2:13 am - Reply

    Hi i live in the Caribbean where the weather is always hot and no matter what i do i can’t seem to keep my koi pond from getting green… Any advise on what can i do to prevent this… We would like to see them but the water is always green..

    • Koi-Care staff December 1, 2015 at 2:48 am - Reply

      you really have to address your water chemistry first. You need to make sure that the water doesn’t contain the necessary nutrients that allow algae to grow. Sunlight and warmth are one thing but algae needs nutrients like ammonia and nitrites to do well. If you remove that you should have clear water. So test your water and make sure that there is little to no ammonia and nitrites and make sure your filter media has plenty of beneficial bacteria on it to assimilate those nutrients that I mentioned.

  60. Coachmartin November 29, 2015 at 7:37 pm - Reply

    Hey guys I have a koi pond now for about a year and the water has turned a little green color I just changed the filter for the pump. The pond is only 150 gallons and I have a pump for a pond up to 500 gallons and I am thinking about completing a 50/50 water changed to possibly clear up the water. Should I add anything extra to prevent this in the future? The fish seem to be thriving very well I still have all the fish since I started the pond. Any tips on how to try to keep clearer water in the pond. Any tips would be great.

    • Koi-Care staff December 1, 2015 at 2:56 am - Reply

      Need some clarification on the kind of green water you are seeing. Is it green water algae thus giving you a “pea soup” kind of look or is the water a greenish tinge like food coloring?

      I would say like a pea soup kind of thing going on.

      it may just be easier to send this article so you better understand your algae situation. In the article I also talk about effective ways to deal with green water algae too.

  61. Nina December 23, 2015 at 10:17 am - Reply

    Hi i need help with our above ground pond (cement) we built it couple of months ago with water falls and all, with out water filter since we didn’t inted to put fish on it. And then My dad bought 50pcs med size koi, now the problem is we have alge problem since we didnt install filtration. Can i still put filtering system? The size of the pond is 2×4 and 3feet deep. thanks

    • Koi-Care staff December 30, 2015 at 8:22 pm - Reply

      Well, first off I would consider the fact that those fish will grow and with that will come greater biological demand on the system. I’ve created a calculator that will allow you to figure out how many inches of koi are best suited to your pond. Here is the calculator. Second thing is filtration. You could get away with an all-in-one system that will suit your needs for your size pond and be easy to maintain/clean. Something like this should work in your situation.

  62. Mark Miller January 31, 2016 at 11:01 pm - Reply

    I’ve got an 18 month old backyard pond of about 250 gallons (about 5’x7’x22″) in California’s Central Valley (AG area 9). I created a 35 gallon above ground bog filter using gravel & bog plants with @ 150 gallons/hr (actual measure) circulating from the pond via under water pump. The return water falls back into the pond from about a 10″ high pipe to give a little aeration. The pond has a valve to self-fill to replace evaporation. I have also deliberately over flowed the pond to add a few dozen gallons of fresh water a couple of times each summer. Winter rains also create water flush. The pond is in sun with some partial shade.

    The pond has pots with water lilies, cat tails & floating edge plants. There are about 8 goldfish, 3 small and 5 about 5″-6″ long as well as a few dozen rosy minnows that add interest & help eliminate mosquitoes. I steadily remove small to moderate amounts of slimy algae with a net and I have hairy algae on most pond edges. (No snails, frogs or other occupants.)

    Generally things seem to be smooth. Last year I had a Spring bloom of floating algae that turned the water green. That cleaned up and didn’t recur after I adding physical filtration at the pump for 2 weeks & changes filters daily. Annual water tests at a pet shop (just to see) have indicated no water quality issues.

    Is there anything more I might do to increase oxygen in the water and/or reduce nitrogen? I’d like to avoid a recurrence of the algae bloom. But the fish seem active & healthy. I’m thinking of increasing the pump size (currently 350 GPM with a 30″ lift) or maybe physically flushing my bog filter?

    Any suggestions/ideas are welcome.

    • Koi-Care staff March 28, 2016 at 7:41 pm - Reply

      Spring blooms are common largely because nitrifying bacteria haven’t had time to ramp up in numbers to effectively handle nitrogenous waste. It sounds like you are not using “store bought” physical or biological filtration and going the natural route which is good if you can pull it off but I would say that adding Microbe-lift PL to jumpStart your beneficial bacteria colonies will go a long way in controlling blooms. You could think about UV in-line to your pump to deal with green water algae. It effective on bacteria, viruses and other nasties as well (in addition to free floating algae). You could also consider in-line ionization. It, along with UV, leaves no residue and no chemicals are involved. As far as increasing dissolved oxygen the simplest solution I can think of besides the aquatic plants you already have is an air pump and diffuser stones.

  63. Jay February 21, 2016 at 2:13 pm - Reply


    I recently purchased a house with a pond and 12 koi ,approx 40 – 60 cm in size , problem noted that it does not have a bottom drain, please advices as to how we resolve

    Thank you
    South Africa

    • Koi-Care staff March 28, 2016 at 7:35 pm - Reply

      Jay, you can certainly add one the fact. I haven’t done it but I believe a company that folks use is called Advantage Retrofit Bottom Drains -they are usually smaller than the ideal 4″ ( i think they are 2 inch). You would essentially run your piping over the contours of the bottom of the pond to the lowest point where you would place your retrofit drain.
      Good luck!

  64. Marty February 22, 2016 at 10:32 pm - Reply

    I am about to finalize the purchase of a home in the country. There is a small stream/creek that runs the border of the property. There is an “upper” pond with nothing in it and that one feeds the lower pond which has turtles and Koi. That pond in turn, has an overflow drain that feeds back into the creek.
    Are there some basics I need to know about maintaining a “natural” pond? I’ve had man made water features with waterfalls etc. on another property but this will be will be the first time I’ve maintained a natural water feature with Koi.

    • Koi-Care staff March 28, 2016 at 7:34 pm - Reply

      That’s a good situation to have. Most folks don’t have the right situation at their residences to have such a pond but it solves a lot of issues having that much flow in and out of the pond. Just keep an eye on the reproduction of the fish as no pond does well when it gets too crowded. My guess is that your soon-to-be pond has been running pretty smooth for quite a while so I don’t anticipate you having to do a whole lot to care for it. I imagine that you will want to supplement their food source a bit and check the water chemistry from time to time just to make sure everything is on par.

  65. Sra March 18, 2016 at 12:41 pm - Reply

    How do I keep frogs away from my Koi pond.. I don’t like frogs in there.

    • Koi-Care staff March 28, 2016 at 7:26 pm - Reply

      Well, you could consider pond netting. You would have to make sure the mesh size of the netting was smaller than the size of the frogs getting in your pond.

  66. Mae March 26, 2016 at 11:49 pm - Reply

    Help pls.. My koi fishes settle at the bottom of the tank and tend to jerk when it moves.. Ive got a neutral ph of the tank. Can anyone help me please…

    • Koi-Care staff March 28, 2016 at 6:39 pm - Reply

      What about the other metrics of water chemistry like ammonia, nitrites and nitrates? Introduce any new fish recently?

  67. JEANNIE NIEMI April 5, 2016 at 6:15 pm - Reply

    I have a 800 gal lined pond with three 3-4 year old Koi. This spring one of them has a solid 1 ” square patch of white fungus maybe, and the other side with blotchy white from the front side goinf from the front all the way to the tail. Netted the Koi for a better look and it just looked lighter in pigment. Could not determine what it was. Can I still treat the whole pond with Tetra-Pond treatment with the healthy fish too?

    • Koi-Care staff July 11, 2016 at 3:41 pm - Reply

      In this yes, you will want to treat the whole system as opposed to quarantine. You will want to remove any activated carbon from your filtration system prior to adding it though.

  68. Loretta M Smith April 17, 2016 at 1:51 pm - Reply

    Ii have a 600 gal. Koi pond and was wondering what temp should water be to do a partial water change. I want to do a speing cleanup. The evwning temps have just started being in the 40s and day temp 70 forbthe last 2 days. Should i wait a little longer and when can i start adding my barley extract, activated carbon, and microlift bacteria? Thank you

    • Koi-Care staff July 11, 2016 at 3:40 pm - Reply

      yes, when the water is more like 45-50 is when you would want to do that (but only use barley extract if it has worked for you in the past as it can be inconsistent in its effectiveness)

  69. Elizabeth Johnson April 17, 2016 at 11:41 pm - Reply

    We’ve just moved into a new house and it has a fishpond with Koi in it. Do we need to run the water pump and filter 24/7 or can we have it put on a timer? and if we can, what time period would you suggest? Any other helpful tips you can give me to take care of Koi. Any help would be appreciated.

    • Koi-Care staff July 11, 2016 at 3:39 pm - Reply

      All things being equal it is best to run your system 24/7. This is for 3 reasons:
      1) metabolism doesn’t stop in fish so your filtration should reflect that
      2) the beneficial bacterial colonies need the constant aerated water to do well and if they do well your pond does well
      3) if you don’t have supplemental aeration to your pond in the form of say an aeration stone then your pump would be serving that purpose.

  70. Moody May 4, 2016 at 2:02 pm - Reply

    We’ve recently added three Koi to a 1800 Gal line pond with a pump and tetrapond 4phase UV filter leading to a three test fountain in the center. Prior to adding the Koi, the water was incredibly clear. There were pockets of, what I assume to be algae, resting in the bottom (fine, green dust). After adding the Koi, we cannot see past just a few inches of the murky green water. It appears as though they have stirred up the algae. What is the best method for clearing the water so we may enjoy seeing the Koi?

    • Koi-Care staff July 11, 2016 at 3:47 pm - Reply

      So it sounds like your system does not have a bottom drain? The recurring issue pond owners will have with a system like that is that “stuff” will just continue to gather at the bottom and require regular removal via a pond vac. How long has the floating stuff been stirred up? My guess is that it will settle down given a little time but off the top of my head one thing you can do to force the settlement is use a floculator. For example, I carry a product called Accu-Clear that grabs the suspended materials in the water column, clumps together then falls to the bottom however that material will need to be vacuumed after treatment. What you are describing doesn’t sound like actual “green water” because your pond would not be clear at all (before or after addition of fish) so I am curious what got kicked up after adding the fish.

  71. Terry Aston May 11, 2016 at 8:06 am - Reply

    Hi, We live in Udon Thani Thailand where the temperature most of the year is in the high 30’s Celsius. We have problems at times with the pump and due to us not always being here we have purchased a new one. Can you please advise how many hours a day should we have the pump working? Our Thai “Expert” reckons if it is off for more than 4 hours the koi will die?
    Our koi are healthy and getting larger.We feed them by hand every morning when they come to greet us at the side of the pond.

    • Koi-Care staff July 11, 2016 at 3:24 pm - Reply

      hi, what has been the typical schedule of your pump being on and off? How many fish? How big are they? Most often one’s pump is also tied into one’s filtration system and because the filtration system functions to cleanse the water and one of the jobs of the pump is to introduce additional dissolved oxygen into your pond then ideally your pump and filtration should match the amount of respiration and biological process that goes on in your pond. Unfortunately your fish don’t stop respiring and producing waste just because the pump is off however fish all over the world survive in natural ponds with out either. The difference is that in natural systems there is usually a balance struck where biological reducers (microbes and the like) take care of waste products produced by larger organisms and when there is too much waste produced for the reducers to keep up with disease usually proliferates and subsequently some of the larger organisms die off and the balance resets itself. In man-made systems like koi ponds, it is up to the pond owner to maintain that balance using pumps and filters and drains etc. One of the problems with turning your pump off without supplemental oxygen being introduced into the pond is that it not only allows the dissolved oxygen level to fall but it also starves the beneficial bacteria on your filter media (if you have an external filtration system). And this is especially important in hot weather because warmer water retains less dissolved oxygen. If all is equal I would run that pump and filter all the time but if you have to turn it off then opt for night time and try to limit the amount its off.

  72. joel May 29, 2016 at 5:50 am - Reply

    can i put a birds cage together with the koi pond?

    • Koi-Care staff July 11, 2016 at 3:04 pm - Reply

      a bird cage near your koi pond? Sure, just don’t allow the bird droppings in the pond.

  73. Jane Boero June 6, 2016 at 6:59 pm - Reply

    I have a 4′ x 10′ koi pond with 2 koi that are
    2 1/2 ‘ feet long.
    My liner has sprung a leak which I cannot
    Locate . I purchased a new liner but putting
    The fish in another container while I install
    The new one is impossible.
    A number of years ago my husband and I
    Put in a new liner while the fish were in the
    Pond .
    My koi tend to graze on the algae in the pond ,
    The water is clear as I have a uv light.
    I also feed them Koi food.
    Will the koi adapt to eating just the koi food
    Until the new algae grows?
    Thank you,
    Jane B.

    • Koi-Care staff July 11, 2016 at 2:53 pm - Reply

      Definitely, a lot of koi pond owners rely largely on koi food to keep their fish going. Its going to fine and with warmer weather coming algae will come back pretty readily.

  74. Lauren June 9, 2016 at 3:49 pm - Reply

    I just moved into a house and there is a little pond out front. there are two HUGE bushes in front of my bedroom window, which the pond is underneath. The little pond is BEYOND filthy. It probably hasn’t had any care since its been installed, but I really haven’t got that close to check it out. HELP! I’m NOT sure how to even begin cleaning this thing, as I’m sure it would be beautiful and peaceful. Should I just trim the large bushes, or take them completely out?

    • Koi-Care staff July 11, 2016 at 2:51 pm - Reply

      Okay, some preliminary questions:
      What is the footprint size of the pond? How many gallons? Does it have a liner or natural bottom? Does this pond have any kind of filtration like a pump and filter, UV, etc.? Are fish in it now? How deep is it? What climate are you in? Do the bushes drop leaves seasonally? Any other shade trees nearby? The first thing you will want to do is get a water test kit to see what the state of the water is to determine if it makes more sense to drain then refill.

  75. Donna June 17, 2016 at 3:15 pm - Reply

    Hello – I had a local pond company come out and add some water lilies and a water lotus to my pond. They were in tubs. The 2 lilies had gravel on top and the water lotus did not. Now my pond is muddy. It has been 2 days now and not clearing up. The pond guy said it would clear up in a day or 2. Will this clear up soon or will I need to pull out the water lotus and add gravel or small pebbles? Should I clean the skimmer filter out a once or twice a day to assist with this. I was just cleaning the filter once every 2 weeks. I just had my pond cleaned a month ago and it was clear as a bell and now muddy. Please help.

    • Koi-Care staff July 1, 2016 at 8:01 pm - Reply

      Donna, there is a specific type of soil that should be used in submerged aquatic plants and I can’t imagine that places that sell and install aquatic plants don’t know the difference. If you use the wrong kind it will result in a lot of suspended “stuff” in the water for some time. You could definitely put some pebbles on top of that pot (the fish may even be rooting around in the soil and stirring it up more) and even use some flocculator like koi clay. Give it a day or so more and see what happens and defintely clean the skimmer more often if you have the time to do so.

  76. nick August 29, 2016 at 12:17 am - Reply

    I have some algae (green water) in my 500 gallon pond and planning to invest in a UV Sterilizer. I already have a Lifegard Aquatics (UNO) Filter ..which i think is a biological filter. I have a pump which is attached to the filter..and creates a waterfall for aeration.

    I have a few questions?

    Q1. I was looking for a suggestion… to find the right UV System . I dont have a lot of place in my i need to be careful of space as well. I was going to replace the current filter with a all-in-one filter ? However i noticed that all in one filters comes with another pump ..and I already have a pump. A separate UV system (like Aqua) i have seen the videos..but none tells if these are submersible or they sit outside the pond. Will these work with my current setup of filter and pump?

    Q2: I see a some UV Clarifiers and Sterilizers? which ones are better for my setup?

    Q3: Do I need a skimmer as well ?

    Q4: A lot of posts above suggest aeration? Is my cascading (final fall into the pond being 6 inches)..sufficient for aeration ?

    Thanks in advance..!

    • Koi-Care staff August 8, 2018 at 1:24 pm - Reply

      3″ bottom drain
      most skimmers will be compatible with bottom drains
      shoot for 1500 GPH when looking at pump capacity
      You could do a plain waterfall with no biofilter

  77. Jessica wilcher October 24, 2016 at 1:49 am - Reply

    I had a pond that I drained and cleaned I used a house hold cleaner to clean the liner , I filled the pond back up and put clarifier and chlorine remover in the water I waited a week before putting my fish back into the pond. They lived 2 days and then all 10 died
    :(. I am now wanting to try putting more fish in my pond what do I do I added more clarifier and it’s now been over a month since the other fish died.

    • Koi-Care staff February 3, 2017 at 8:40 pm - Reply

      exactly which household cleaner did you use?

  78. nik October 26, 2016 at 6:02 am - Reply


    All tests for water quality seem fine, but my ph level are high and wont come down..I am trying to put some greenclean ph down powder, but it has not helped much. Nitrates almost none, Ammonia none, no chlorine….phosphate seems little high side.

    Please suggest whats a good remedy to keep ph within range.

    Also, I have noticed excessive foaming in the pond after i added the air stone….its not only near the waterfall…but all over the pond. I have a small pond 400 gallons..and 2 cascading waterfalls to keep the DO levels fine…but as suggested I have added an additional air stone to keep DO levels fine. I ready somewhere that foaming may be caused by excessive DO levels…not sure if that is relevant. But do excessive DO levels harm my fish ?. I have 3 medium sized KOI there….getting ready for their first winter.


    • Koi-Care staff February 3, 2017 at 8:39 pm - Reply

      Hmm, that strange that you are having such a pH problem with a concrete pond-the concrete will act as a buffer. For now try the vinegar and see if you can get it to an acceptable pH then re-assess. You have lots of aeration and no overcrowding so it’s strange. Normally if you have overcrowding you would have lots of carbon dioxide in the water which would create carbonic acid and lower pH ( and you have alkaline water so it’s a mystery…for now). As for the filter, you can do a gentle spray off of the filter media but you don’t want to take a pressure cleaner to it or anything. Also remember that the surface of the filter media is a place where beneficial bacteria congregate…but it’s not the ONLY surface- many surfaces, cracks and crevices anywhere in your pond will also house beneficial bacteria ( that’s why ponds in the wild are able to thrive).

  79. Wendie Benson July 23, 2017 at 4:09 pm - Reply

    hi, just wanted to advice to point me in the right direction, my daughters boyfriend lives in the phiippines its warm most all the time. He as a very large natural fish pond that his aunt is letting him use soon to raise koi fish he wants to buy them as babies and raise them until they get bigger. He was out cleaning the fish pond cause it hasnt been used in quite some time, he came upon alot of leeches and we were wondering if the leeches will hurt the koi fish? He was thinking of draining all the old nasty water out and either spreading salt or some other thing over the muddy walls and bottom and then scraping all that muck and salty earth out and then putting in all new fresh water from neighboring stream to re fill it will that be a good idea ? then once that is done when he buys the baby koi then put them in, i dont know what else is a good idea to deal with that, and if you could give me some pointers on how to get this pond ready in advance of putting like close to 50 baby koi fish in i would appreciate it . and does the care of the pond need any chemicals for maintence? or what is your advice to keep this pond in a good condition for the baby koi to be happy and healthy fish? any other things we should know about to help like using snails, other kinds of fish to eat leeches that get along with baby koi as they grow up? and also i am a bit concerned because the fish pond is far away from any electrical source so i dont think a filter or pump would be available to use with this pond so i was wondering if you have any opinions or pointers as this situation is all new to me. thankyou for your time

    • Koi-Care staff August 8, 2018 at 12:46 pm - Reply

      One thing I would ask that may alleviate most of the issues here is: how close is this stream that you mentioned? You can save yourself a whole lot of time and effort if you can get the stream to enter say on one end of the pond then exit out the lower side. That takes care of your water quality issues, filtering, etc. Leeches? That’s a good question and not something that has come up before. I am wondering if perhaps a little salt in the pond would deter the leeches? A treatment of copper would kill them as they are invertebrates. Leeches would probably find their way onto the fish otherwise.

  80. Frankie March 10, 2018 at 10:36 pm - Reply

    I have about 3500 gal pond first spring with it.came with the house I lost about 10 fish this winter but have about 20 8” to 12” koi left. Today in about 3 hrs temp raises about 5 degrees to 56 degrees water temperature. In about 3 hrs. All of a sudden there is some white stringy stuff floating on top of water. I think it’s still to cold for them to be spawning so what could this be????

    • Koi-Care staff August 8, 2018 at 12:23 pm - Reply

      Thats a weird one. So it looks to be associated with increasing water temps so it could be possible that the fish are more active and rooting up the bottom releasing some gunk that has built up. I dont know if its warm enough for fungus yet but that could be that color. Sorry im not more help but this is a new one on me.

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