I have a new tank about 4 weeks old. The water is testing fine and the 2 clowns and 3 damsels are happy but there is a grean alge that is taking over the tank. Is this normal for a new tank. I am running the lights 8-9 hours a day. the blue ones and MH. I added the clean up crew from saltwaterfish.com for a 100 + gallon. Is there something that i can do to get it under control?