Aqua Euro USA Hang On Back Protein SkimmerOur Aqua Euro USA Hang On Back Protein Skimmer maintains a clean marine aquarium ecosystem by effectively eliminating dissolved organic compounds (DOC), which is a must for keeping a pure, healthy environment for your aquarium inhabitants. This protein skimmer is made with high quality thick acrylic (not plastic) construction and requires only 3½" between tank and wall. The needle wheel pump is included and this protein skimmer eliminates waste in aquariums up to 90 gallons. Easy to install and use; just hang on the back of tank and plug in. Aqua Euro USA's Protein Skimmers are highly favored among aquarists due to their superior craftsmanship, body design, performance and affordability.