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Thread: inherited pond/koi - guidance needed before our koi fall on hard times...

  1. #1
    Join Date
    Apr 2008

    inherited pond/koi - guidance needed before our koi fall on hard times...

    Hi all, we need a candid assessment of the koi pond that's landed in our lap and whether it's viable or an accident waiting to happen.

    We recently moved to Colorado and the house we bought came with a koi pond whose size I calculate at about 375 gallons. From my reading here it seems like the depth is just minimally OK for the four good-sized koi inhabiting it - it's about 4' deep, fish are in the 14" - 16" range. Straight walls, no rocks other than a waterfall feature external to the pond (local sandstone rocks mostly). No bottom drain and would be hard to retrofit with one, I think.

    The current fish wintered OK with an ice-melt unit (just to keep a small aeration hole) but we did lose a fifth one as the water was coming up into the 50s...there was a fair bit of debris under the ice and nitrites were too high, so I guess I am not totally surprised. (We moved here in December when they were shutting down metabolically.) I understand that early spring is the most dangerous time because the bacteria are awake but the koi immune system is not fully up and running.

    Once it got warm enough we seemed to have an algae bloom and a two-week struggle with green water while we scrounged for info and tried to understand the equipment we'd inherited. We did a series of partial water changes and some aggressive filtration (a four-stage UV filter with the plastic bio-filter material as stage four plus a 12"x12" physical filter). This improved water clarity and kept the nitrites low but not zero. Adjusted pH as needed and applied some salt as stress relief when the nitrites were at their highest. Same filtration system is now in place and runs 24x7.

    Last weekend we did a full pond cleanout and complete water change. Everybody survived the experience and we had nice clean water, nitrite zero, pH just right, alkalinity golden etc. All the numbers looked great. But now after only 4-5 days nitrites are already creeping up into stress zone. Not as high as before, but trending upward pretty fast. Water is fairly free of debris and filters are clean and rockin'. What's wrong?

    A second question: Right now the only aeration is the little waterfall. Is that enough or do we need an underwater bubbler of some kind? Previous owner did not have one as best I can tell, just a vertical tube with waterspout in the center of the pond; we powered the waterfall using the same pump, so it's the same water flow but the water is more thoroughly broken up over the rocks, so I'd guess ours actually oxygenates better than the old one. I just don't know if we need more.

    Sorry for what are no doubt very basic questions - I did a fair bit of searching here before posting but wound up wondering if our pond configuration might just be wrong to start with, so thought it best to just describe it and ask you gurus!

    Thanks in advance,
    Hoping-not-to-be-a-koi-menace in Colorado

  2. #2
    Oyagoi CarolinaGirl's Avatar
    Join Date
    Sep 2006
    South Carolina
    OK...where do we start. First...do you have an ammonia test kit? If so, what are your ammonia levels? Also need to know pH and nitrite readings. Also, you say the pond is 4' deep....but it's only 375 gallons. so if it's round, then it would only be 48" round and 48" deep to get a volume of around 375 gallons. At any rate, that pond is too small for koi. Koi need a minimum pond size of 1000 gallons, and at least 300 gallons per fish. If you are having nitrite problems, you are probably also having ammonia problems and it's because the fish are overwhelming the filter system. You honestly would probably be happier with some goldfish in there. They only need about 50 gallons each and come in nice colors. They just don't get as big as koi do.

  3. #3
    Oyagoi gcuss's Avatar
    Join Date
    Jul 2007
    Maple Falls, WA
    Hi and Welcome to the forum,

    Carolina Girl has some good points. I wonder if you could tell us how you came to 375 gals? With a 4 foot deep pond, as pointed out, even at 4X4 it's 400 gals. Anyway, grab a tape measure and if you'd like some help post the dimensions. It's important to know your exact gallons for just about everything you'll need to do.

    Ok, small list for you here, then more accurate advice to follow... please post:

    Dimensions of pond
    Actual readings (in numbers) of your Ph, Ammonia, Nitrite in your pond.
    Temperature of the water
    A reasonable description of your filter system (ie: submersible pump? external pump and location of intake in the pond, describe the matting, plastic bits that are in the filter, wattage of the UV light, pump size)
    *pictures speak a thousand words*

    Also, stop feeding if you are.
    Add salt to .3% if the nitrites are still up.
    See if you can get Kh, Gh and Nitrate numbers as well.

    Good luck, and welcome again.


  4. #4
    Join Date
    Apr 2008
    Thanks for the prompt response (and help!).

    A couple initial answers - I lack an ammonia test kit so that will have to wait until later.

    First, I may have miscalculated the volume, and unfortunately it may be even less, more like 345g. 375g was my recollection from having measured it some months back, but redoing it now I see that the pond is shallower than I thought. Dimensions are 38w x 75l x 28d. Using an online calculator that gets me only 345. Am I doing this correctly? If so, it sounds like way too small for four koi based on your responses. (If so, how have they lived this long? - at least a few years...)

    I am attaching some photos of the setup, as suggested.

    Current water conditions are:

    nitrate - 0
    nitrite - .5 - .75
    hardness - 75
    alkalinity - 80
    pH - 7.0
    temp - 52 but was up to 58-60 most of last week, and we're warming up again so will top 55 probably this afternoon and hold there

    The pumps for the two filtration systems are submersibles. The UV/filter unit is a Bioforce 1313 "1000+ UV" with a 9 watt bulb; it's external to the pond. It has three stages of physical filter (doughnut-shaped, about 2" thick each, of graded degrees of coarseness) and then a chamber at the bottom with the plastic bio-filter media. I assume you know the type. The other filter is just a perforated square frame with Pondmaster fine polyester media filter. You can see it (dimly) in one of the pictures.

    The pump intakes for the filters are a few feet away from the outputs.

    Hope this gives you a better idea - sorry for the lack of detail in the initial post but I just don't know what's relevant and what isn't. I will get some ammonia readings as soon as I can get a test kit but perhaps this info gives you something to go on. Obviously concern #1 is the pond volume...can you confirm my calculation?

    Many thanks again for your collective patience!
    Attached Thumbnails Attached Thumbnails inherited pond/koi - guidance needed before our koi fall on hard times...-koipond-001.jpg   inherited pond/koi - guidance needed before our koi fall on hard times...-koipond-002.jpg   inherited pond/koi - guidance needed before our koi fall on hard times...-koipond-003.jpg  

  5. #5
    Oyagoi gcuss's Avatar
    Join Date
    Jul 2007
    Maple Falls, WA
    Ok.... well, I don't think you need a rant on how unsuitable that pond is for koi...

    Let's look at it this way:

    There are fish in there, I'm assuming they've been there for sometime and are alive (and I'll assume reasonably healthy) so let's deal with what we have.

    First, with a pond this small, you'll have to feed extremely light. Once you get your ammonia tester, let this be your guide. Your goal (although tough to achieve in this situation) is 0 ammonia and 0 nitrites. I have no idea what this will equate to in regards to volume/frequency of feeding but I'd suspect it would be extremely light if at all.

    Without a bottom drain you're going to have to clean the mulm off the bottom on a very regular basis (daily) with a pond vac, or something. I suppose you'd be able to use a wet/dry vac, but will be kind of a painful proccess . Another option is a tiny water garden pump with a hose/tubing on the intake side, prime the pump and use it as a vacuum with the discharge water going somewhere else besides the pond.

    You'll need to clean the foam covering the intake of your submersible pumps daily and you'll need to clean out your filters frequently as well. When you clean your filters (importantly the bio media portion) rinse and wash with pond water only so you don't kill off the bacteria with chlorine in your tap water. This might be another use for the mini vacuum pump for cleaning the bottom of the pond. Stock up on medication for the fish, you're going to need it.

    In all reality, the maintenance schedule for a pond like this, with the fish you have in there is a nightmare. I'm not saying that you can't do it... but your water parameters (temp/nitrite/ammonia/ph.. the works) are going to swing wildly throughout the day and night and will probably always be a stressful environment for your fish creating various health problems along the way.

    My best suggestion would be to continue to educate yourself, have a look at what you've got going on in your life and decide if you'd like to get into this hobby. If you decide that you enjoy it enough to invest money and time, then it goes without saying.... GRAB A SHOVEL AND GET TO IT!!

    However, if the few things I've laid out for you seem to be too much work and not enough time to get it done (we're all busy people these days) and the fish don't really interest you that much, I'd suggest you place the koi if possible with somebody else with an actual koi pond. (craig's list etc. if you don't know anyone personally) Get some plants, maybe one or two goldfish and enjoy a peaceful water garden.

    End of the day, your pond, your fish. But let's be fair to the koi.

    Good luck, and if you decide to stick with the hobby, bookmark this forum. The advice and experience offered here is second to none. I started out just like you (only my first "pond" was even smaller than yours ) and I've got a long way to go before I'd even deem myself competent at koi keeping.


  6. #6
    Join Date
    Jun 2006
    Los Gatos, CA
    Gcuss has a lot of good advice for you.

    You are actually in better shape than I was when I inherited my pond. I had 10 koi and 15 gold fish in a 750 gallon pond with only a submersible pund for circulation and the 'filter was buried in the ground so there was no way to clean it other than to back flush it into the pond

    It has been a slow process to upgrade the pond as I have had time. Still a ways to go.

    YOu can keep a koi alive and healthy in this environment. Many people do, and many here started that way. It isn't ideal, and if you are not very careful, you might lose some, or all, of your fish.

    Check your input water. high percentage water changes and a trickle through system will help. Watch for chloramine in the tap water.

    DIY projects for the future:

    Bigger pond
    bottom drain
    better circulation

    What you have will never be good, but it can be enjoyable until you decide you want to make the improvements needed to get there.

  7. #7
    Join Date
    Apr 2008
    This is kind of what I figured, disappointing as it is to hear. I'm not sure how the previous owner kept these poor guys hanging on, but it sounds like life cannot be that happy for them. They seem fine, but what do I know...and we did lose one.

    So, two queries by way of thinking through my options:

    1. Could this pond support a single koi in harmony with some other hardier residents such as goldfish? I.e., should I think about finding new homes for three but keeping one just for interest?

    2. Are there any ready guidelines for determining a fair price if I sell them? And how can I confirm that they're viable? I don't want to sell a sick fish. Caveat emptor, but I do feel a fairly strong degree of responsibility there.

    Thanks again for all the rapid and detailed input. (Grant, thanks especially for spieling out what daily life would be like if I wanted to make a go at it...that was an eye-opener!)


  8. #8
    Daihonmei MikeM's Avatar
    Join Date
    Dec 2003
    Orlando, Florida
    The prior owner may have been very fastidious in regular maintenance and fed lightly; or, the koi were very small and have grown to be larger than the pond can support. Koi can live a long time on once per week feedings in a cool climate.

  9. #9
    Oyagoi gcuss's Avatar
    Join Date
    Jul 2007
    Maple Falls, WA
    Hey Edward,

    No problem on the help. It was a tough realization for me too. But now I've got 3 ponds, healthy fish, and I enjoy the hobby immensely.

    As for keeping one koi... In reality? If the one your keep is finished growing... yes. It's never going to be ideal, but the world's not perfect. Koi like company, so a couple nice little fantails or something would be good for company.

    I don't want to discourage you from koi keeping but I think the best solution would be to place the koi you currently have due to their size, and pick up a very small koi and a goldfish or two and raise one yourself. I think if you get a small koi, knowing that you'll place it in a new home when he gets a bit bigger, you could learn a lot about husbandry while your at it.

    As far as what they're worth? Would need decent pictures of them to say for sure... But my guess would be not much. I think the priority would be finding someone who could help you out by taking them off your hands. Post some pictures if you like and then you'd know for sure. Only a very small percentage of koi are worth anything and I'd suspect that whomever originally built your pond, and bought the fish didn't import show quality fish from Japan.

    Health wise...?? To say for sure you'd have to inspect each fish carefully looking for sores, damage to fins, lumps/bumps/bruises, gills, and scrape each fish and check for bugs with a microscope. As long as the fish is visually OK I would assume a potential new owner would have the means to investigate further if required.

    Best of luck,


  10. #10
    Join Date
    Apr 2008
    Thanks so much, Grant. I may try to snap some pix of the fellas and post them for comment. Not thinking to make real money on them, but don't want to be a shmuck either...

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