Mini suction cups and a length of black acrylic cut from some random cover I had laying around. Might have been part of a glass cover hinge.
My filter return is in one corner; found it worked best to put one cup on the back wall and the other half way along the side wall. This created a curved section that the floaters couldn't get into and the tension from the curve helped keep it in firmly set in the suction cups. You could also silicone it to top edge of the tank if you can't find inconspicuous cups but the cups are much easier to slide up/down to adjust for changing water levels.
Last edited by Knotyoureality; 10-13-2012 at 05:14 AM.