Ah, I see. Looking as his screen again I can see what you're talking about - the low growth int he area that is submerged. The alternative would be to add a second drain. I just trimmed the bottom 1/2" off my screen the other day. it was just growing red turf. That stuff seems to grow well in the lower light areas of the screen, like at the corners and side edges. I trimmed the edges off my screen (3" actually) and no red anymore. That was just incidental to reducing the screen size to make it right w/r to amount fed.