Water Quality Problems

[Violetmuse]

I have an approx. 1800 gallon koi/goldfish pond which was set up about fifteen years ago (9'x9' square, ranging from 2' along the sides to 5' in one corner). The pond currently holds three very large koi (over two feet long, added two years after we first set up the pond), two smaller koi (maybe 10 inches long, added last summer), and I'd say about twenty goldfish ranging from 10 inches down to three inches. (Some may still be original to when we set up the pond, but most of those started as baby fish before we got the koi; last year was the first time in a long while that we saw any new babies appear.) We also have a few minnows that were caught in local waters.

We had problems with water filtration for the first few years, then about ten years ago we set up a DIY biological filter which has (until now) worked out very well. The filter setup is a submersed pump which is covered with coarse filter media held in place by a net bag; this draws into the bottom of a large barrel filled halfway with layers of lava rock and coarse filter media, topped in summer with water hyacinths. The water then moves to a second barrel filled with layers of coarse sand and finer filter media. From there it splits - half the water spills directly back into the pond, and the other half goes through a UV light and up to a waterfall. (It used to all go to the UV & waterfall, but that proved to be too much water pressure for the falls so we had to divert some of the flow.)

Up until this summer we didn't have any problems with this filter. The water was clear, we didn't have much algae growth, and the fish seemed healthy and happy. This year...the water is clear, but it's filled with a lot of swirling fine detritus that's not sinking to the bottom and not getting filtered out. After an unseasonably warm winter, the fish had a bit of a rocky start in the spring - some listlessness, some cloudy and bulging eyes - but they seem to have bounded back to be as lively as ever, even if they still don't look as good as they should. I've also got more algae growth than usual, some stringy stuff that clings to the bottom of the planters/sides of the pond, and some thick stuff that I have to keep scooping out of the second barrel. There's also a lot of gunk clinging to the roots of the water hyacinths, which I don't remember seeing before - usually it all settles to the top of the lava rocks and creates the kind of mud you'd find in a swamp, but this year it's not doing that, or at least not yet.

I've tested with strips and the pH, nitrates, nitrites, ammonia levels all seem to be good according to the instructions that came with the strips. I've also done a couple of extra water changes, and I've added more bacteria and Stress Coat plus the usual barley and plants.

I did have to rinse the filter media around the pump because it got clogged, which usually happens once or twice when we turn the filter on in the spring before everything levels out. I generally don't rinse out the barrels because I don't want to rinse out all of the bacteria, but I'm starting to wonder whether maybe I should rinse them? Maybe replace some of the filter media, then add more bacteria? Or do I need to look into building a bigger filter system, maybe add a third barrel or something?

Other than adding chemicals, is there anything else I can do to try to eliminate the algae growth?

Is there anything I can add to get the detritus to settle to the bottom of the pond, or do I need to look into getting a vacuum or skimmer of some kind?

Any help would be appreciated... And if I'm just being over-anxious, any reassurances would also be appreciated. :\ I've never had any problems before so I don't know if I'm making a mountain out of a molehill this year or what...

 

[Meyer Jordan]

You are overstocked. Because fish continue to grow and multiply you have added fish mass and additional demand on your biofiltration (and mechanical filtration). Adding bacteria is a waste of time as there is no new surface area for them to colonize. You have Two(2) options:
1) Increase the bio-and mechanical filtration and possibly water flow.
2) Re-home at least 50% of your fish.
Addin chemcals (algicides etc) will only cause water quality to further deteriorate.

 

[AlyssaFish]

Perhaps the water that's being diverted from the waterfall could be used to fuel a bog filter? In case you're not aware, bog filters are basically gravel beds filled with bog plants. The water passes through the gravel, leaving behind detritus to feed the plants and bacteria growing there. The plant roots also strip the water of waste products that can feed algae.

They say that a bog garden should make up about 10% of the gallonage of your pond. It's a lot of setup, but once functioning it only needs seasonal cleaning and it's gorgeous. I made bog filters for my little 160 gallon pre-formed pond using planters on each side. Not a very natural look, but the preformed wasn't natural looking to begin with anyway and I didn't have the budget for better.

 

[Tula]

Do you have a way to clean your barrel filters? We back wash our sand and gravel filter and I can tell when it's time, it traps solids and needs to be dislodged.

 

[Violetmuse]

Thanks for the replies! I had no idea that a couple new koi could throw things off kilter so badly. :\ I can't rehome any fish (at least not without building a second pond), but a bog filter would be doable. I have a stock tank I was planning to make into a raised garden bed, I would just need to add a liner and some stones to turn it into a bog.

As far as backwashing the filter - I do let the yuck out of the bottom of the barrels when I do my water changes, but that's about all I do to it. I was afraid of messing up the biological system so I didn't want to disturb it too much. Should I use the hose on it at all, or just let the pump do its thing while I drain?

 

[sissy]

Koi produce a lot of waste and with that many other fish it just added to the problem .Goldfish breed to much for my tastes .

 

[Meyer Jordan]

Adding a "bog" may help, but with this many fish, it would need to be of considerable size to fulfill your needs.
Why would you have a problem re-homing some of your fish? Others in your area may be quite happy to have them.

 

[Tula]

Thanks for the replies! I had no idea that a couple new koi could throw things off kilter so badly. :\ I can't rehome any fish (at least not without building a second pond), but a bog filter would be doable. I have a stock tank I was planning to make into a raised garden bed, I would just need to add a liner and some stones to turn it into a bog.

As far as backwashing the filter - I do let the yuck out of the bottom of the barrels when I do my water changes, but that's about all I do to it. I was afraid of messing up the biological system so I didn't want to disturb it too much. Should I use the hose on it at all, or just let the pump do its thing while I drain?

I do my back washing with a blower, so it's air bubbles dislodging the debris.

 

[Tula]

Only my opinion, but I don't see you being over stocked with koi......you have too many goldfish. My pond is 1700 gallons and I have 4 koi. I made the decision to rehome all my goldfish and extra koi, keeping it at 4...with no exceptions.

 

[Jimmy Gibson]

Only my opinion, but I don't see you being over stocked with koi......you have too many goldfish. My pond is 1700 gallons and I have 4 koi. I made the decision to rehome all my goldfish and extra koi, keeping it at 4...with no exceptions.

I have three huge Koi (24" plus) three medium (18" plus) one small about 8".... And over three dozen 1 1/2" long babies from the first spawn and about a dozen 3/4" long from the second spawn.......although I struggled at first things are great now...... But the point of my post is I have two friends that have long time ponds, twenty years plus, one has a pond about the gallons as mine and has three times the large Koi as I have, the other has a smaller pond than mine and has twice as many large Koi than I do...... One rarely checks his water quality and the other never has checked theirs, these are two ponds with what I have read is way over stocked..... But have beautiful healthy fish, that live year after year, it's a mystery to me how some ponds thrive breaking the normal rules and others do not ......Sarah says I am obsessive compulsive with water testing , but I have cut it back from every day to three times a week ..... And Tula we didn't go to the Louisville Koi show because I was afraid I would buy some.... Lol Jimmy

 

[Tula]

I have three huge Koi (24" plus) three medium (18" plus) one small about 8".... And over three dozen 1 1/2" long babies from the first spawn and about a dozen 3/4" long from the second spawn.......although I struggled at first things are great now...... But the point of my post is I have two friends that have long time ponds, twenty years plus, one has a pond about the gallons as mine and has three times the large Koi as I have, the other has a smaller pond than mine and has twice as many large Koi than I do...... One rarely checks his water quality and the other never has checked theirs, these are two ponds with what I have read is way over stocked..... But have beautiful healthy fish, that live year after year, it's a mystery to me how some ponds thrive breaking the normal rules and others do not ......Sarah says I am obsessive compulsive with water testing , but I have cut it back from every day to three times a week ..... And Tula we didn't go to the Louisville Koi show because I was afraid I would buy some.... Lol Jimmy

Ha ha on the Louisville Koi Show! I was planning on attending, but was out of town. I would've liked to meet fellow koi keepers, but would not buy more koi.

I've read articles, that it's quite possible to keep an over stocked koi pond, with excellent filtration. I don't see 5 koi in 1800 gallons, as over stocked, but I wouldn't keep the goldfish in addition to koi.

 

[Violetmuse]

I've had almost the same number of fish for years, because after the koi got big enough (and ruined all my water lilies) they kept the numbers of fry pretty much down to nil. So that's only six new fish last year compared with previous years, and the water quality up until this year has been pretty good - the filter system plus the UV light have kept things kosher. But I guess a combination of over-feeding plus a really warm winter and those six extra fish have finally tipped the balance.

I can't get rid of any of them...they're beautiful, and they have such quirky personalities, and I get attached. But I'm excited to try a bog filter now, and hopefully that will help.

 

[Jimmy Gibson]

Ha ha on the Louisville Koi Show! I was planning on attending, but was out of town. I would've liked to meet fellow koi keepers, but would not buy more koi.

I've read articles, that it's quite possible to keep an over stocked koi pond, with excellent filtration. I don't see 5 koi in 1800 gallons, as over stocked, but I wouldn't keep the goldfish in addition to koi.

I made another friend during the pond building process/ going to local pond tours and he went to the Louisville show and bought four fish..... He was wanting to give me three adult fish.... I respectfully declined..... Don't know how I am going to get rid of 4 dozen baby Koi..... But I also know Sarah and I, there are four of the babies that are pretty kool.... Lol Jimmy

 

[Meyer Jordan]

I've had almost the same number of fish for years, because after the koi got big enough (and ruined all my water lilies) they kept the numbers of fry pretty much down to nil. So that's only six new fish last year compared with previous years, and the water quality up until this year has been pretty good - the filter system plus the UV light have kept things kosher. But I guess a combination of over-feeding plus a really warm winter and those six extra fish have finally tipped the balance.

I can't get rid of any of them...they're beautiful, and they have such quirky personalities, and I get attached. But I'm excited to try a bog filter now, and hopefully that will help.

Utilize the 'bog' filter in conjunction with your present biofiltration, not in place of it. Abandoning you present biofilter will gain you nothing considering the size 'bog' that you are considering.

 

[Jimmy Gibson]

I've had almost the same number of fish for years, because after the koi got big enough (and ruined all my water lilies) they kept the numbers of fry pretty much down to nil. So that's only six new fish last year compared with previous years, and the water quality up until this year has been pretty good - the filter system plus the UV light have kept things kosher. But I guess a combination of over-feeding plus a really warm winter and those six extra fish have finally tipped the balance.

I can't get rid of any of them...they're beautiful, and they have such quirky personalities, and I get attached. But I'm excited to try a bog filter now, and hopefully that will help.

Unlike you

I've had almost the same number of fish for years, because after the koi got big enough (and ruined all my water lilies) they kept the numbers of fry pretty much down to nil. So that's only six new fish last year compared with previous years, and the water quality up until this year has been pretty good - the filter system plus the UV light have kept things kosher. But I guess a combination of over-feeding plus a really warm winter and those six extra fish have finally tipped the balance.

I can't get rid of any of them...they're beautiful, and they have such quirky personalities, and I get attached. But I'm excited to try a bog filter now, and hopefully that will help.

I was in the same situation as you..... Mine was too many fish in a pond that had not cycled yet, first order an API Master test kit if you don't have one already..... Check it every day..... If the ammonia gets to. 25 do a 50% water change, this will buy you about two days...... If you keep feeding..... Buy some Pond Prime, you can get it off Amazon..... When my ammonia got to. 50 a couple of times that's when I used the Prime..... But at the end of the day what kept me going until my pond cycled was water changes, and the same can work for you until you get your Bog working. Everyone will tell you to quit feeding them and that is sound advice, but I could not bring myself to do it. This is a perfect time of the year for Bog building and you have time to get alot of plants going, in a fairly short period of time. And yes you will have a good size water/electric bill with the addition water changes, but realistically if you can afford to have a Koi pond you can afford two or three months of high water bills... Jimmy