I have a 39 gallon saltwater tank. I have this horrible red algae on all my live rock and some of the shells of my crabs. I have tried everything to get rid of it. Little light, few water changes, lots of water changes. My latest technique is "Liquid Gravel Vac". But, nothing seems to get rid of it. I have lost all my corals. I only have crabs, a shimp, live rock and 2 clown fish left in the tank. I'm hoping someone out there can help me. I have tried to put large snails in the tank. But, they don't live a full day. I have spent so much money, but, I keep telling myself it can't be this difficult. Could someone out there help me?