Basic sorts of Aquarium Filtration Systems

Mechanical, biological, and chemical filtration are all important
By SHIRLIE SHARPE Updated on 12/10/19
Goldfish (Carassius auratus) swimming in large rectangular aquarium .
Max Gibbs / Getty Images
A healthy aquarium depends on maintaining clean water, and doing so requires some means of filtering out the water to get rid of contaminants and purify the water. Technically, there are three means of filtering aquarium water:

Aquarium Filtration Systems

Biological filtration refers to the method by which beneficial bacteria break down ammonia and nitrite and transform them into compound nitrate, which is far less toxic. For beneficial bacteria to thrive, oxygen-rich water is required , also as a surface that bacteria can attach to, like rocks or sand. All aquariums should have some provisions for biological filtration, and with very small fish populations, this alone could be sufficient to sustain the aquarium. However, in most aquariums, biological filtration are going to be only one method that’s combined with others.
Chemical filtration may be a process by which chemical additives remove dissolved wastes from the water. the foremost common method for chemical filtration uses activated carbon .

Mechanical filtration is what most of the people consider as true filtration—machinery that removes solid particles from water by circulating water and straining it through some quite aquarium filter. it’s important to know that mechanical filtration alone isn’t sufficient since it doesn’t remove or convert ammonia, nitrate, or nitrite within the water. Mechanical filtration serves to get rid of free-floating waste before it decays into harmful substances, and to be beneficial the filter material must be cleaned or replaced every two to four weeks. additionally to filtering contaminants from the water, mechanical filtration assists in aerating the water.
To effectively maintain an aquarium, a filter should run all the water within the tank through the filter a minimum of fourfold each hour. When choosing a system, concentrate to what quite filtration it offers—biological, chemical, or mechanical. Some systems combine the various sorts of filtration, to varying degrees of success.

There are eight common sorts of filtration systems you’ll choose between .

Box Filters

Also called corner filters or internal filters, these were the primary aquarium filters available for home aquariums. Although less common than within the past, they’re very inexpensive and may be loaded with a spread of filter media. Many box filters are compact units that stick with the glass inside an aquarium, making them suitable for little aquariums of 20 gallons or less. Corner filters are often used for hospital tanks wont to treat sick fish because fish owners don’t wish to take a position tons of cash fixing a tank that’s used infrequently. Their less powerful intake flow also makes box filters popular to be used in breeding tanks with tiny fry.

Some types require an vacuum pump and air line to supply the movement necessary to maneuver water through the filter. These systems create air bubbles that also enhance chemical and biological filtration.

These systems home in price from $8 to $30.

Canister Filters

Canisters are powerful mechanical aquarium filters best fitted to medium- to large-sized tanks—those larger than 40 gallons. Because canister filters are positioned outside the tank, they’ll be easily concealed behind or beneath the aquarium stand. These large units provide excellent mechanical, chemical, and biological filtration. Canister filters are pressurized to force water through the filter media, instead of allowing it to flow past it as other filters do. This makes them ideal for heavy loads. Adding a biowheel increases the biological filtration capacity of the aquarium filter. On the negative side, canister filters are difficult to require apart for cleaning and maintenance, and that they are difficult to urge primed and restarted afterward.

Canister filters are excellent for saltwater aquariums or those with many living plants. Costs can range from $90 to $500.

Diatomic Filters

Diatomic systems are specialized aquarium filters that “polish” the water by removing very small particles. In design, these are almost like diatomite swimming bath filters, which operate by pumping water through a layer of very fine particles to wash the water clean.

Diatomic filters are most frequently utilized in temporary situations when fine particulate , like diatomic algae, may be a problem. Because a diatomic filter is employed just for special situations, some standard filters are made with diatomic inserts in order that they may serve a dual function when needed.

Costs of diatomic filters range from $40 to $100.

Fluidized Bed Filters

Relatively new, these systems are very efficient biological filters that utilize sand or silica chips because the filter medium. These units hang from the rear of an aquarium, where water is pumped through it then down through a mass of sand or other media. the tiny particles provide a superb area for the bacterial colonies to thrive.

Most units don’t accompany water pumps, which require to be purchased separately. These units don’t provide excellent chemical filtration, but mechanical filtration is moderately good because the sand media traps suspended particles.

Costs for fluidized bed filters can range from $50.00 to $150.00.

Power Filters

Sometimes called hang-on-back filters, power filters are the foremost commonly used sort of aquarium filter, largely because they provide excellent mechanical, chemical, and biological filtration simultaneously. the quality power filter hangs off the rear of the aquarium and sucks water up through a siphon tube. they’re simple to put in and straightforward to take care of . Mechanical filtration is achieved by water flowing through a filter pad or floss. Chemical filtration is provided by the water flowing through an activated charcoal filter, and biological filtration is obtainable by beneficial bacteria that form inside the filter cartridge. Power filters could also be combined with a biowheel to supply increased biological filtration.

Power filters home in price from $10 to $150.

Sponge Filters

The sponge filter is fitted over a tube from an influence head or vacuum pump . As water is forced through it, bacteria will grow and establish a biological filtration. Sponge filters also provide mechanical filtration, although they clog quickly if there’s excess debris. they’re excellent for tanks with fry, because the sponge prevents young fry from being sucked through the pump. Sponges are good for a hospital isolation tank, as a sponge from a longtime aquarium quickly provides the tank with nitrifying bacteria.

When the sponge filters are cleaned, it’s important to try to to so with aquarium water, as water will kill the beneficial bacteria that’s growing on the sponge.

Prices for sponge filters can range from $5 to $40.


Also called wet/dry filters, trickle filters are designed to show the water to the maximum amount air as possible. this is often accomplished by allowing the aquarium water to trickle over a container of media, like plastic balls, strands, or floss. This exposure to air and water fosters large colonies of beneficial bacteria that break down wastes. These are especially popular for saltwater tanks, but are getting increasingly popular in freshwater aquariums, as well. Chemical filtration is provided by placing chemical media within the filter.

The biggest drawback is that the incontrovertible fact that they clog fairly easily. the utilization of a mechanical pre-filter eliminates or reduces that problem.

Trickle filters are often fairly expensive, with costs starting from $30 to $300.

UGF (Under Gravel Filter)

The UGF (under gravel filter) is another aquarium filter that has been around for an extended time. It utilizes a plate filter that’s placed under the substrate, and an vacuum pump that pulls the aquarium water down through the substrate, taking the particulate with it. However, biological filtration is restricted with this sort of system, and chemical filtration is non-existent.

The UGF is inexpensive, easy to line up, and it’s relatively maintenance free once running. On the downside, UGFs tend to clog and aren’t good choices for aquariums with live plants

Costs of UGF systems range from $8 to $60.

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