Pond Boss Forums POND CONSTRUCTION Renovating a Pond or Lake? Acquiring 1/2 acre green Koi pond in need of TLC

In the current condition your pond will not have filamentous algae nor submerged weeds due to the constant action of Koi "working the sediments" that results in low transparency water. You will not have clear water as long as you have at least 10-20 adult koi present. IMO if you can reduce the number of koi to around 10 I think you could have water clarity in the range of 12"-16". Clearest water would be most common during the colder months when koi are not as active.

I don't have much easy or simple advice for your specific unique problem. To have a large mud bottom koi pond that is clear is to my knowledge not practical without extensive cost likely beyond your means. I really don't have any good options for you. Maybe try visiting a koi hobbyist forum for some of their suggestions and opinions.

It will be very difficult to maintain a specific number of koi when there are males and females who would annually reproduce numerous offspring. Single sex koi would be an option which is what I would investigate as a possibility. However this would take an experienced person to accurately sex the adults. An mistake in identification will put you right back to too many koi and a muddy murky pond. To get a single sex koi pond you would need to drain the pond or lower the water to very low pool (depth) to capture all the koi for sorting and removal. Lots of work. A complete pond renovation (fish kill) I assume would not be acceptable to you.

Lowering the pond water would also allow you to accurately see the depth of the bottom muck and capture the koi. It will be difficult to remove the bottom muck from the rocky bottom but it could be done with significant cost. The previous owner assumed that if large sized rocks covered the bottom the water would remain clear - obviously now a bad concept or idea.