Often just called skimmer, is mainly intended for installation in private pools. A suction opening with a freely moveable skimmer flap as well as a skimmer basket behind is characteristic for a surface skimmer. The suction effect of the filter pump reduces the water level in the casing of the surface skimmer while the skimmer flap is simultaneously pulled back into the casing of the surface skimmer. Thus, the most contaminated water surface is primarily captured and directed toward the filter system. The number of surface skimmers depends on the shape and size of the water surface as well as the circulation performance of the filter system.