How Does an Aquarium Pump Work?

Aeration pumps take advantage of the force air places on water in a tube. As air is pumped into a water tube, the continuous stream of rising bubbles “drags” water along its upward motion. Aeration filters are very inexpensive and commonly used in small aquariums up to 20 gallons. A vibrating pump creates air pressure along a tube and is connected to either the base of the intake or the return part of the filter. If the pump is connected to the return tube, a siphon is used to bring the water into the filter. If the pump is connected to intake tube, gravity is used to return the water.

Power filters are magnetically driven. They are attached to the filter, usually sliding together and acting as a single unit. Power pumps use two magnets; one is attached to an impeller inside the filter, and another is attached to the motor. As the magnet on the motor spins, it causes the magnet attached to the impeller to spin as well. The spinning impellor pushes water along a tube, either to or from the filter.

External pumps are maintained outside of the aquarium and have three classifications: centrifugal, diaphragm and peristaltic. Centrifugal pumps, like the attached power filter pumps, are magnetically driven. A spinning impellor forces water to the outsides of the impellor housing and through a tube. The impellors and motors are larger and much stronger than those on power filter pumps. They can pump large volumes of water through filtration system in short periods of time and are usually used on larger tanks (55 gallons and up). Diaphragm pumps deliver water in pulses as a motor opens and closes the diaphragm, forcing water to enter and exit a chamber. Peristaltic pumps employ rollers along flexible water tubes to pump water. As a roller glides over the tubing, the water is pushed in the direction of the roller. Peristaltic and diaphragm pumps are used by more experienced hobbyist who want to maintain very specific water quality parameters.

Submersible pumps are magnetically driven pumps that are placed inside the aquarium. They are efficient, convenient and small, but come with a few caveats. Submersible pumps generate heat and could end up overheating the aquarium. Since it is submerged, great care and attention must be given to the electrical lines to avoid shorts and electric shocks.