Filter Types

Even if you're already aware of the importance of an aquarium filter, the sheer number of available filter types can be overwhelming. To help clear the confusion, we've put together a list of some of the most common types of aquarium filters and supplies.

Undergravel Undergravel filters are biological filters that sit on the bottom of an aquarium. Water is pulled down through the gravel and filter and pumped back up through a connected lift tube. This water flow promotes the growth of bacteria that neutralize toxins in the aquarium. Undergravel filters are often used by beginning aquarists. They can't be used in saltwater aquariums unless the tank contains only fish.

Hanging
Hanging aquarium filters are probably better known as power filters. Power filters hang on the side or back of the tank, where they filter water that has been pulled out of the aquarium by a siphon tube. The processed water is then pumped back into the tank.

Hanging filters are often preferred over other mechanical filters because they are easier to inspect and clean. Many power filters also provide biological and chemical filtering.

Canisters
Canister filters are similar to power filters but focus more on mechanical filtration. Canister filters need to be cleaned consistently to rid them of accumulated waste that would otherwise decompose and reenter the water stream. Canister filters can also hang on the back of the tank but are usually located beneath it.

Powerheads
Powerheads are submerged water pumps that can work in tandem with undergravel filters. Powerheads are often attached to lift tubes to enhance the flow of water. Powerheads can also be attached to a wave maker, a device that turns them on and off to give the aquarium water a wave-like motion.

Air Pumps
Some aquarium filters work together with air pumps, such as corner filters, undergravel filters, and certain protein skimmers. Air pumps can also be used simply to improve water circulation, making filters more efficient.

Wet/Dry
Wet/dry filters, or trickle filters, work by trickling water over aquarium media that is not submerged, encouraging bacteria colonization by increasing the air/water surface area.