The AquaClear Powerhead Water Pump is a versatile pump that can be used in various aquarium applications for superior performance. It provides the important function of circulating and aerating the water for a healthy environment and also drives under-gravel filters. You can also connect this pump to a protein skimmer. The motor is completely submersible and includes flow control as well as a venture aeration feature that increases surface agitation and gas exchange. A unique reverse flow feature is included in the 50 and 70 models to help promote beneficial bacterial growth from the bottom up.