I have som steff in my fish tank that I think is algae. It first appeared as white fuzz floating around in the water in the morning. I looked into the tank and this stuff was just floating around everywhere. I was like oh no! my fish are gonna inhale this stuff and die!!! but then, In the afternoon though it was completely gone. when I looked more closely I saw all my decor and the glass had a thin white fuzzy coating, so I guess It just had settled. Anyway, It is growing the most on the ground under the filter flow. some of it is brown, but mostly it is long and white. all of it is hairy looking. I tried turning off the lights and washing off the decorations but it just came back. What is it, and how do I make it go away.