Are you using Glut? If so what dose? Also remember in the beginning months most tanks get green dust algae on their glass. Most all my tanks go through that especially ones with higher light. I've always just used an algae magnet to keep it clean and have found as the tank matures and balances out that algae just seems to run it's course (unless your actually getting something like BBA on the glass) and goes away. I only run an algae magnet over my front glass every 2 or so weeks and that is to just remove the natural layer of bio-film that builds up on it. You can run a 2 hour break in your light cycle if you want but honestly I have never done that.