I have a 240 using sump / filter sock filtration. I change the filter socks and wonder why - there is almost nothing in them. My problem is poop on the floor. Here is the setup: 2 built-in overflows, 3 1600 GPH powerheads at the bottom, an FX5 with the return and output about 6" off the floor, sump returns pointed down, 2 return pumps each 1800 GPH. Poop stays on the bottom and just goes around the base of the rocks and stumps. I can't get it to go up in the water to get captured by the overflows. I do 30-50% water changes weekly, but I don't like looking at the poop. How can I get it to go up within 2" of the surface? If I put any more flow in it the fish will be stuck on the walls! I try relocating the flow but it just relocates the turds. 
