Brown algae and hard brown crust

[Flymac1]

If I'm reading your posts correctly, you have 4 decent sized koi in a pond that's only 6' X 6' X 2' deep? If so, that's a big part of your problem (imo) - your pond is WAY too small for even 1 koi.

Other than that, I'm still not really understanding the ground water pump thing. What is your purpose of overflowing the pond twice a day with ground water? Have you done any testing of your water parameters? Are there any plants in the pond, other than the one water lily?

I just figured it would mimic a flowing stream

 

[brokensword]

I just figured it would mimic a flowing stream

A flowing stream though would move the bottom forward and on; in this case, you'd have to stir the whole pond AND have some sort of flow 'on'. Not exactly the same and I'd not want to disturb the bottom too much as that will surely clog your filter faster. Most will tell you here to lift your pump off the bottom just so you don't clog with heavy/large debris. It sounds like maybe you need to upgrade your filtration, esps with larger fish and smaller pond. Research a bog and see if it'll work for you. There's a lot of us that never do water changes or have flow through and have nicely clear water with chemical balance. That's what you aim for.

Any pics? Especially of your filtration system?

 

[JamieB]

Yes, this was info definitely helps. Your pond bioload is too much, the bacteria can’t break down the waste fast enough, so I see a few options. 1) expand the pond, this is something that you should keep in mind. Koi are a large fish, and recommendations say 1000 gallons per koi, but it can be fudged a bit by really good filtration. The best filter we here have found is a properly sized bog filter. But unless you make a bog bigger than that pond, keeping 4 koi aquarium n that volume will continue to give you issues.

Option 2) build a big bog. Still a good idea, as mentioned above. The idea is to imitate Mother Nature’s natural filter, water comes in at the bottom and percolate through about a foot or more of gravel, where tons of bacteria break down the waste, then at the top, plants use the results to grow, thus cleaning the water. 1/3 of the surface area of the pond, or more, is ideal, but with a larger fish load, go bigger.
Option 3) rehome the koi to a bigger pond and get smaller fish. Less than 600 gallons of water is more suited to about 6 standard type goldfish, common, comet, shubinkin. These only reach about a foot in length from nose to tail, with longer tailed variations having tail extending beyond that foot mark.

 

[Flymac1]

A flowing stream though would move the bottom forward and on; in this case, you'd have to stir the whole pond AND have some sort of flow 'on'. Not exactly the same and I'd not want to disturb the bottom too much as that will surely clog your filter faster. Most will tell you here to lift your pump off the bottom just so you don't clog with heavy/large debris. It sounds like maybe you need to upgrade your filtration, esps with larger fish and smaller pond. Research a bog and see if it'll work for you. There's a lot of us that never do water changes or have flow through and have nicely clear water with chemical balance. That's what you aim for.

Any pics? Especially of your filtration system?

Thanks so much for the information

 

[Flymac1]

Yes, this was info definitely helps. Your pond bioload is too much, the bacteria can’t break down the waste fast enough, so I see a few options. 1) expand the pond, this is something that you should keep in mind. Koi are a large fish, and recommendations say 1000 gallons per koi, but it can be fudged a bit by really good filtration. The best filter we here have found is a properly sized bog filter. But unless you make a bog bigger than that pond, keeping 4 koi aquarium n that volume will continue to give you issues.View attachment 135404
Option 2) build a big bog. Still a good idea, as mentioned above. The idea is to imitate Mother Nature’s natural filter, water comes in at the bottom and percolate through about a foot or more of gravel, where tons of bacteria break down the waste, then at the top, plants use the results to grow, thus cleaning the water. 1/3 of the surface area of the pond, or more, is ideal, but with a larger fish load, go bigger.
Option 3) rehome the koi to a bigger pond and get smaller fish. Less than 600 gallons of water is more suited to about 6 standard type goldfish, common, comet, shubinkin. These only reach about a foot in length from nose to tail, with longer tailed variations having tail extending beyond that foot mark.

Thank you for the response. I have two Koi’sthat are about a foot long and the other two are about 8 inches long

 

[JamieB]

Koi are a heavy waste fish, with a large mass. If you are getting the brown gunk at this point, it will just get worse as the fish grow. That is why I made the suggestions I did, to give you the options. A bigger pond pond and bigger filter are ideal, or if you can’t, then in the late spring, reduce the fish load.
The pond could be enlarged by depth as well as by width/length. If you can’t dig down for some reason, go up! There are threads about above ground ponds. I originally had an above ground pool I turned into a pond, it had never been chlorinated, filled with just well water, and had sat stagnant until I added fish and a small pump. But beware if you try that option, a new pool may or may not have been treated with algicides, so I recommend you wash it with plain water a few times first.

 

[Flymac1]

Thanks for all your suggestions, I’m going to start applying some of them now.