One Scum bug oil-absorbing sponge absorbs an amazing 40x its weight in oil and pollen. When placed in a clean pool or spa, the Scum bug improves filtration and helps to eliminate formation of a scum line. It will not get clogged in water lines. Simply place the Scum bug in your pool's skimmer (fits all) or free-float in your spa. When 1 side is scummy, flip it over. When saturated, squeeze out, clean and reuse. Under normal conditions, 1 Scum bug should last an average swimming season.