Learn About Aquarium Canister Filters

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The filter is the most important part of your aquarium. Without proper filtration, no fish or plants will survive.

If your tank is beginning to be a challenge or you find yourself spending too much time doing maintenance and not enough time just relaxing and watching it, you could be experiencing "ageing tank syndrome".

A canister filter can turn an unrewarding challenge and a chore into a pleasure and a breeze.

To prevent turning your aquarium hobby into an aquarium nightmare, an upgrade in the type of filter you use is usually a very simple answer.

An aquarium canister filter will turn your whole aquarium world upside down. What was an unrewarding challenge and a chore will become a pleasure and a breeze.

An aquarium canister filter is a larger filter-in-a-drum (about 15" to 28" tall) that sits out of site under your tank in the aquarium stand. It has an intake valve and an outflow valve on the top where flexible tubing is attached. The intake brings water from the tank into the filter where it swirls through the interior of the canister, being routed through all of the media, cleaned and sent back to the tank through the outflow valve.

Canister filters usually perform 3-stage filtering.

Canisters are essentially a closed system. All top brands have easy-to-use snap closure brackets that keep them sealed and without leaks. Depending on the manufacturer, each houses a configuration of media-containers that perform different functions. Unlike your current under gravel filer or tank-back power filter, most canister filters offer complete three-stage filtration. (See Learn About Aquarium Filtration for details of stages)

Water enters and passes through a filter pad that traps large particles and debris (mechanical filtration). It is then routed through several media trays that hold water-cleaning media: First a layer of carbon that takes out colors, odors, chlorine and early-stage ammonia in the water by actually absorbing it into the carbon. (chemical filtration)

Then the canister works its magic. The "bacteria bed" of most aquarium canister filters is in a chamber holding bio-media, ceramic rings, bio-stars, bio-balls or some other type of media made to house bacteria cultures that will change the toxic nitrites into less-toxic nitrates (biological filtration).

Depending on the size of the aquarium, the canister may hold two, three, even four trays of media.

Good canister filters are easy to maintain. Easy-on, easy-off, easy open, easy close. No priming, no mess.

A good aquarium canister filter will be easy to shut down and easy to start again without a lot of priming or water spills, so that when it is time to clean or adjust media you are not faced with a sloppy or frustrating job.

Good canister filters have lots of options for using the media that suites your tanks' particular demands.

A good aquarium canister filter should have flexible media trays so that you can choose what media you want to use in each tray. That will allow you to use charcoal, zeolite, toxin-absorbing pads, water polishing pads, and/or bio balls and rings in any quantities and any time your tank may need it. Some even offer water polishing micron pads that will make your water virtually sparkle as well as filter out many pathogens such as ich tomites (that cause ich disease) and algae cells.

A good aquarium canister filter should be quiet, energy efficient, and require minimal maintenance.

A good aquarium canister filter should be quiet when operating and require minimal maintenance. Most need to be cleaned or adjusted only 2-3 times per year. When it does require cleaning or media adjustment, it should be easy to work with. Baskets that hold media should be easy to get in and out. The mechanical-cleaning pads and chemical-filtering carbon should be very easy to get to, as they are the most frequently cleaned or changed. (Many aquarists use an ancillary tank-mounted power filter for added mechanical and chemical filtration because you can change those functional cartridges with just a quick lift-out and replacement of the cartridge right from the tank top without disturbing the canister filter at all.)

A good aquarium canister filter should have a high-quality impeller. Most name brands today have impeller motors that will last for 10 years or more.

Larger tanks and more heavily populated tank needs much more biological filtration than smaller or sparsely populated tanks because more fish produce more waste. An aquarium canister filter is overkill for a 10 gallon tank. However for 20 gallons and up, it is a huge benefit: better filtration, fewer fish deaths, and MUCH less maintenance.