OK guys, I'm having a bit of a problem. I do water changes every 1-2 weeks, water is stable, ammonia 0 nitrite 0 and nitrate very low. However, I have an algea problem. On my powerhead, they have the rubber suction cups that stick to the glass. This is where I first noticed algea growth, but I ignored it. Recently, about two days ago, I noticed a few spots on the glass. No big deal, going to clean it this weekend. In about three days time, it was immensly bad. I saw it on the rocks, the plants, all over the glass. I did a 20% water change, scrubbed the algea off everything, and now I'm letting the filter suck everything up.. However, I was just wondering what was the cause of the algea and how to prevent it. Note, my tank is no where near sunlight.