I have a problem with a small 25G tank set up using only rock and glosso. Algea has always been a problem in this tank, but I have been able to get rid of it using shrimps, ottos and SAE's. But, lately there has been this green film on the water surface. The water is crystal clears, it's just on the top floating about. I have been using paper towles to get it of, but I always leave a few tiny pieces of it, and in a day or two it grows right back. I have never heard about alge looking or acting like this. Does anybody know what the heck it is, and any advice on getting it out?