Hello from Seattle

Hello all, I have a 1500 gallon concrete pond with about 40 fish, roughly half koi and half comets. The pond is a bit over stocked, but the fish seem content overall. Cheers, yellowruby

Welcome to the forum yellowruby..
at least you know you may be over stocked

Welcome as well. With only half the population as Koi, if you have good circulation and filtration, you should be fine. But you are very marginal at this point. I have the same situation and because of my superior filtration "Doc bio filter" and circulation everything is fine.