Now my water is crystal clear (finally). It cleared by itself (using a small hang-on-tank filter with polyester batting in it) over a period of several weeks. But now the water has a residual green tint to it (sort of like there was some food coloring in it). I am running the same filter with carbon in it, but the green doesn't seem to be disappearing fast. Any ideas? Dave Gomberg, Experimenta San Francisco CA USA gomberg at wcf_com