A diaphragm pump, also known as a membrane pump, is simply a pump that moves fluid. They're highly versatile creations: they can be used in anything from wastewater treatments to the production of artificial hearts. And you know the filter on your little aquarium at home? Diaphragm pumps help make those things as well-specifically, the part of the filter that pumps air). In a diaphragm pump, the diaphragm is often made out of Teflon. When it's squeezed, it pushes fluids either out one side or out both sides.