Hello, I have a 29 gal Rift Lake tank with no plants, one 20 W strip light, a pH of about 8.3, and high GH and KH. The substrate is a calcareous material, with landscaping of "moon rock", a shell-based agglomerate. For reasons which I don't understand, blue green algae proliferates like crazy in this tank. Why is this happening and what should I do to prevent it? Thanks, Dinyar