An aquarium pump is usually used to circulate and oxygenate the water in an aquarium. The main function of the aquarium pump is to produce a continuous flow of water. This continuous water assists in aerating the water and keeps your system clean by sending solid contaminants toward the filters. It works by introducing fresh water into the aquarium and then discharges it through a diffuser or nozzle and produces a current that ensures the water flow in the tank.