Air pumps are used to oxygenate the aquarium water. You should also buy air tubing and an air stone to go with your air pump. Air pumps can also be used in filtration systems, such as under gravel filters and corner / box filters. Air pumps can be noisy but are popular because when used as part of a filtration system they are a cheaper alternative to internal and external filter systems. We stock a variety of different air pumps for different size aquariums and budgets.