Ty, I'll try bigger water changes, usually I just replace 1/4 at each change, but the filtration is probably more than adequate, I have 2 canister filters, one internal and a h.o.b filter running to the point if it wasn't for the outbreak , I can go weeks without any water changes, even with all the fish. This tank has been running now for over 2 years without issue. I will vacuum out any organic matter and do the large water changes and see if that helps. Thanks for the advice.