So I was playing around with screen and slot pipe size and ended up throwing away my mature screen only to decide that my original screen and slot pipe size was the best. I replace the 5"x9" screen with a brand new roughed up screen 3 or 4 weeks ago. But now the growth I'm getting is really strange,I am getting nice thick green growth on the bottom left hand corner of the screen but nowhere else. The rest of the screen keeps growing this chocolate brown algae like stuff? The brown growth does not wipe right off like jelly but it does scrape off much more easily than let's say turf or hair algae. When I clean the screen it is left bare white with the exception of the green corner . I have noticed that when my pump has been freshly cleaned it has more than enough GPH for the 5" screen,,but after a month I lose almost half of that flow. ( monitoring flow with stopwatch and gallon jug) . Is the low flow causing my strange growth?