Canister Tank Filters

Canister filters are designed to handle a greater flow of water than hang-on filters and are a great choice for larger tanks. They are capable of providing 3 stage filtration:

• Mechanical
• Chemical
• Biological

Although they can and do filter biologically, they lack sufficient chamber space to hold sufficient biological media. You should use them with other biological filters.

One advantage of the canister filter is their versatility. You have the choice of customizing them to your aquarium by loading different filter media (micron pleat cartridges, sponges, poly filters, etc.). Keep in mind that the more filters you add, the more they’re going to reduce your flow of water through your filtration system.

Some people use the canister filters by themselves but you also have the option of using them in parallel or chaining them to other filtration units.

Although some canister filters are small enough to hang on the side of aquariums, most are large enough that they need to be stored under the aquarium. However, storing the filtration unit below the aquarium poses issues in pumping the water back up to the aquarium (also known as ‘head pressure’). This distance can severely inhibit flow.

The canister filters are the workhorse for most saltwater aquarium hobbyists because they strike a nice balance between cost and performance. And their size and capability makes them appropriate for most aquariums.

Choosing The Right Canister Filter

Like many aquarium equipment, you should buy the largest filter you can afford. For the most part, you can’t overfilter your aquarium and it’s better to grow into a filtration system rather than suffer growing pains.

1. Flow Rate
   This is measured by gallons per hour and the manufacturer usually gives this information on the product manual or packaging. However, they make assumptions that may not be necessarily true for your aquarium setup.
   • Head Pressure
     They assume that the unit will be level to your aquarium water level but if you keep the canister filter below in your aquarium furniture, the power to pump the water back up to the aquarium reduces flow.
   • Filters
     The manufacturer assumes you only have the standard filters installed but the more you have, the more it reduces flow.

   I recommend having enough flow to filter your aquarium water 6-10 times per hour. Click here to learn how to measure or estimate this for your aquarium.

2. Functionality
   Make sure your canister filter can take all the filters you’re looking for. Some of the smaller ones will lack the ability to take numerous filters.

Canister Filter Maintenance

• Make sure you can easily get to your canister filter. Otherwise, you’re less likely to clean it or change the filters.
• If the manufacturer sells any tools to make your job easier (or drier), buy it. If you neglect maintenance, your saltwater aquarium will suffer and the easier maintenance is, the more likely you’re going to do it.
• Purchase extra filters and keep a reserve supply. Some filters can be reused if cleaned and prepared. However, having extra filters on hand and just swapping out new filters takes minutes and makes maintenance a snap.
• Having dirty filters impede the water flow and are less effective than clean filters. Change them once a week.
• Because of salts, organics, calcium, and other debris, you should take apart and clean the filtration unit at least once a month, including hoses.