ISTA Mini Surface Skimmer I-511 CHARACTERISTICS: Effectively draws the dust and protein to the skimmer which assures a crystal clear water surface.This creates a healthier and safer environment, as it allows effective gas exchange and proper light for plants. Allows surface water flow to get through from all directions without clogging. With self-floating water inlet chamber, it automatically adjusts itself with the change of water level. Works perfectly with hang on filters and other middle size filters.