First let me say any advise would be appreciated.My scrubber has been running for about a month and a half, no algae. My screen is double with both screens being 10 inches wide and 11 inches deep I have four cfl's with actual wattage of 42 watts per bulb. Pump is 500GPH. I have some algae growing on the bottom of my screen that is submerged but none above the sump water line. Plenty of algae on the bottom of the sump and on the motor but none on the screen. I have only four fish right now in a 120 gal corner tank with a return pump of 1350 gph. Some green algae on my rocks and brown starting on my substrate. I guess something needs improving but I don't know what. In advance, Thanks for the help.Ken