The Reef Octopus Classic BH-2000 Protein Skimmer is a favorite hang-on back skimmer. Capable of filtering aquariums from 130 to 208 gallons, the Classic BH-2000 features an easy to install and operate design in which the pump is mounted inside the aquarium. To install, simply place the skimmer on the back of the aquarium, mount the pump in place, adjust the intake strainer and it's ready to skim. The Reef Octopus Classic BH-2000 is constructed of high-quality acrylic and equipped with a highly-efficient Aquatrance pinwheel pump, which produces an ideal mix of water and air for optimal waste removal.