All u have to do is change the direction of ur intake tube. Instead of having it point perpendicularly down towards the bottom of the tank, u direct it to the surface. Make the intake tube come just below the surface. This will suck off all that surface scum ( piranha keepers know wat i mean, cuz live feeders leave oil residue ) If u ar using a penguin with a narrow 1 piece intake shaff it is quite easy to bend and reshape. Other types, including canester filters, u can use the python water changer tube. Mount the gravel cleaner under surface and attach the tube to the intake of ur filter. This also increases the oxygen capacity of ur tank cuz it is moving the surface water.
