I played with my returns for about 2 days before I found a setting that clears the surface nice and fast. The key for me was to develop currents that would carry to debris to the skimmer area, but a "dead spot" right in front of the skimmer so the stuff would slowly get drawn in once it made it there. almost any current around the opening of the skimmer seemed to carry debris away from it, even if it was aimed right at it