The sides/front/back and my rock in my tank are covered with a kind of brownish "hard" algae but are not in clumps, but instead in round circles or so. I noticed that this algae only came during this winter since I left my curtains open so my room would get some light. Is the sun causing this? And if I close my curtains all the time, How do i get rid of the algae stuck on my rock, since I have my Java moss growing nicely, and I don't want to ruin their colonies. The algae is also growing on the leaves of my other plants. Help? Btw, Does the algae harm my plants?