You all seem to have a huge base of knowledge in this area, I need it. I have a 55 gallon with some decent sized goldfish taking up residence. I foolishly went with sand as the substrate. I'm running a penguin 350 h.o.band a sunsunhw392. I'm doing a 20 percent water change weekly. The tank had never been completely clear and since I put up the sun sun last week the clouds have taken over it looks like a bacteria bloom on steroids and the fish are suddenly at the top trying to get air . Any help or advice appreciated my fish are my babies I'm wigging out. Thanks for your time