I think Green Spot Algae (GSA) is one of those algaes that plague a planted aquarium. At least for me, I haven't been able to succesfully stop it from covering the glass, and have to do regular "window washing" at least once every two weeks. I get jealous of the folks who manage to post their aquascape and never seem to have a speck of GSA. How do you do it? Any one have any suggestions? Anyone know what causes GSA? -John N.