First Tank Guide Tank Logo
First Tank Guide Home

Canister Filters

Filtering Your Aquarium Water

(The First Tank Guide)

What Is a Canister Filter?

Canister filters are aquarium filters that remove the water from the fish tank through an intake tube, sieve, or valve, run it through filter media in a pressurized canister, and then pump the filtered aquarium water back into the fish tank via spill way or spray bar.

How Does a Canister Filter Work?

Canister filters draw water up a lift tube and out of the aquarium into an external filter chamber or canister where the water is pushed through a series of filter media to clean the aquarium water. The Canister Filter Diagram direction of flow varies between models and brands of canister filters, and can be bottom-to-top, top-to-bottom, back-to-front, center-out, or outside-in, depending on the particular brand or model of canister filter. This aquarium filter media provides chemical, biological, and/or mechanical filtration, depending on what kind of filter media you choose to use in the canister filter.

After the water has gone through the filter media in the sealed canister, it is pumped back into the fish tank. Canister filters always use water pumps to move water, since their system is sealed. Most models of canister filter have integral water pumps, usually either built into the cover or built into the base, but some models of canister filter require a separate external water pump.

What Maintenance Does a Canister Filter Require?

Depending on the brand and model of the filter, and the type of media used, the maintenance requirements of a canister filter will vary. Generally, canister filters allow you to use a variety of filter media. Many have baskets, cartridges, media bags, or isolated chambers that you can put your favorite media into to provide the right kind of filtration for your particular aquarium set up. Some media needs to be rinsed out regularly, while other media needs to be replaced. Check the manufacturers recommendations for the type(s) of filter media you are using to better understand the necessary maintenance for that filter media.

In addition to the maintenance required for the filter media, you will also have to periodically clean the tubes and the pump on your canister filter. This can be done easily with aquarium tube cleaning kits sold at most pet stores.

What Should I Be Aware Of with a Canister Filter?

Canister filters are very efficient filters if used and maintained correctly. A good canister filter gives you the advantage of selecting the type of filtration appropriate for your tank by customizing the filter media, rather than being stuck with the manufacturers pre-made media cartridges. A canister filter usually has lower maintenance requirements than a comparable power filter, because the water is forced through the filter media, rather than being allowed to flow over or around the media. Also, most canister filters return water to the tank through a spray bar, reducing evaporation and current.

Remember, with a canister filter, as with any other filter, you need to replace any carbon in the filter frequently, as carbon that has become saturated with waste can begin to release toxins.

Canister filters are especially good for medium to large tanks, as they can filter a large volume of water efficiently.

Canister filters can be configured to provide biological, chemical, and/or mechanical filtration depending on the filter brand and the needs of the aquariist. Remember to remove any carbon from the tank or filter before you medicate (if the carbon is working, it should remove the medication from the tank in under an hour, in which case your fish won't get treated).

"Wow! That was amazing. Far beyond any level of detail I expected. Thank you so much. Your advice makes perfect sense, and I will follow it. Thanks again for what you do."
April 18, 2009
More Comments
"Thanks again Keith! That was exactly what I needed to know. By the way, I think your site is the most informative and comprehensive that I have found. Before I found it, I was getting confusing and conflicting information from other sites, and sometimes it just didn't even make logical sense or was just plain wrong. Thanks for taking the time to put it all together in a logical and easy to read format."
June 14, 2011
More Comments