Fluval SK-400 Surface Skimmer is a compact skimming device that attaches to your filter intake to eliminate the oily film and organic debris from the water’s surface. By continuously drawing water from the top, it clears away surface scum, improving gas exchange and light penetration in the aquarium. The SK-400 is easy to install and self-adjusts to varying water levels, helping to keep your tank’s surface crystal clear and your aquatic environment healthier.