Aquarium power heads are submersible water pumps that can be used to draw aquarium water through undergravel filters. They can also be used as transfer pumps to move aquarium water to and from the aquarium without the splashing and disturbance to the aquarium that buckets or other means of transfer can cause. Some of these aquarium power heads come with special "venturi" tubes to inject air into the output stream to further oxygenate the water, and other aquarium power heads have an automatic swivel mechanism that cause a natural current or wave effect in the aquarium. Like other pumps, aquarium power heads from Aquarium Pumps and More come in a wide variety of sizes to accomodate different applications and aquariums.