Ok, I know its a free floating single celled algae and I know it probably started because my tank is in a room that is very bright from the sun entering through the window. A week and a half ago I put up venician blinds behind the curtains and now the room is fairly dark in the day time, however the algae keeps coming back despite me doing lots of water changes. I did a 50 percent and the a 30 percent the day after, then another 50 percent a few days after that. Now its been 4 days or so since my last water change and it so soupy I'm afraid my plants aren't getting enough light and will parish. My ph is about 7.3 my temp is 82, and my amm, nitrite is 0, my nitrate is about 10ppm. I add co2 by diy and my tank is a 15 gallon tall. It is under a 40 watt PC light, and my co2 is normal on the little indicator in the tank. Any suggestions about how to get rid of this stuff, should I put carbon in the filter? I currently don't use carbon. I'm going insane here, ahhhhh!