My waterfall scrubber currently grows a nice crop of almost black dark green, some hair algae, but mostly stuff that comes off pretty easily when I scrape it. Sometimes with extra yellowish slime here and there. It seems to work fine to reduce Nitrates and Phosphates, but I don't seem to get the hair algae lighter green growth that others seem to get. The scrubber is two sided, with 30 watt red and blue LED lamps - with a pretty decent flow. The lamps are 3 inches from the screen on each side. Light cycle is 20 hours on, 4 off every day. I get lots of algae, but not the luxuriant green growth I have seen in pictures here and on the other site. the screen has been in use for at least 4 months at this point, I would call it mature. Any suggestions? Increase flow? Add Iron?