When you used the filtersock did you get a felt sock bout a 200 micron rating. Not sure if I mentioned this but after placing my return pump in it I attached the hose to the pump and zip tied the sock closed around the tubing to prevent bubbles being drawn in from the top since mine is submerged. Also get rid of that 90 degree elbow on the return. I use eheim 16/22 tubing connected directly to the return nozzle on the tank. The filter socks with the draw string is much better than the ones with the plastic hangers in the top I had to cut those off. Just remember that the sock will become a nitrate factory if not changed out often.