Aquarium Components: Air Pump
An air pump is useful for powering air stones (porous stones attached to the air pump with tubing) to supply supplemental aeration and circulation and to promote gas exchange (oxygen in, carbon dioxide out) at the water surface. Certain filters such as under-gravel filters are also powered with air pumps.
Two primary types of air pumps are available for aquariums:
The simplest design is the vibrator/diaphragm pump. These pumps are widely available and affordable. The pump may have single or multiple ports for connecting air tubing, and some models may have a controller to regulate the amount of air flow from the pump. Piston/rotary-vane pumps are more complex and usually more expensive than a vibrator/diaphragm pump and are generally reserved for use in very large systems.
Typical aquarium air pumps have ports for standard size air tubing that can then be connected to air stones. A check valve should be placed in line in the air tubing between the air stone and pump to prevent back siphoning of water from the tank to the pump in the event of a loss of power.