My tank has grown very hazy in the past few days. It is a dark green kind of murky hue to the water in my 55, and I can't see across! What the heck is this- I did 2 30% water changes in the past 8 days, the ammonia and nitrites are at 0, so it's no bacterial bloom? It's very ugly and unsightly, I also changed my filter media carbon. Anyone have this problem before...it's basically dirty water that won't go away-the fish seem fine however