I have a 90 gallon tank with a DIY CO2 injector and 160 watts of light. I have the problem I have always had and that is I am getting brown algae everywhere the light hits. On the top of rocks on driftwood on plants and on the glass. But only on the top, not underneath where the light doesn't touch. Any ideas for a newbie. Thanks. D. Andrew Claxton aclaxton at infonet_isl.net