How Does a Canister Filter Work? Back To Basics

A canister filter is a self-contained aquarium water filter that contains filtration media outside of the tank. 

Some aquarium filters work by being submerged into the water, and the opposite case is true for canister filters. Canister filters stay outside and below the water level of the tank in order to function properly.

 Because they can hold more water and pump more gallons per hour, canister filters make good choices for aquariums that are large (40 gallons or more) or have aquarium life with excessive bioloads (such as turtles).

How is a Canister Filter Different?

Canister filters are extremely good choices for those with large aquariums or those with large fish, and they are generally more expensive than filters that hang on the sides of tanks. They are more powerful, some even reaching up to 200 gallons per hour of filtration.

They Need More Maintenance

Canister filters require more maintenance than disposable filters of those submerged in the water. They are a self-contained unit that collects all of the nasty debris from your aquarium, which means they need regular cleanings and media changes. 

Filter media such as carbon eventually loses its ability to filter water because it has been used to its capacity, and therefore must be replaced. This really depends on how big your aquarium is and how dirty it tends to get. 

Dirtier tanks will require more filter media changes and canister filter cleanings in order to keep water parameters at favorable levels. Despite this, canister filters’ benefits could far outweigh the monthly cleanings they require

Choose Your Filtration Media

Most filters that require submersion also require that you buy disposable media filters that are specific to their brand. 

This means that unless you buy your own reusable filter media bags and filtration gear, you cannot choose the filtration media that best suits your aquarium needs. 

With canister filters, you can tackle specific water parameter problems because you are able to choose and switch out filter media with ease. 

Canister filters often have trays with sponges inside to help catch debris, and on top of those trays is where your choice of filter media goes.

No More Overcrowded or Messy Aquariums

Switching from an in-tank filter to a canister filter will free up a lot of room in your aquarium and allows for better control of the water flow. 

Canister filters come with control valves on both the intake and outtake tube that increase or decrease the amount of water allowed through, giving the aquarist more control. 

A spray bar that can attach to the side of the aquarium is common, and when the spray bar is pointed at the side of the aquarium wall it silences the water flow. 

Canister filters are easily hidden beneath or next to the aquarium stand.

How Does a Canister Filter Work?

Canister filters are kept outside and below the aquarium and therefore make good use of gravity in order to pull the water down into it and a motor to pump the water back into the tank. 

Canister filters pull water out of the tank through an intake tube using a mixture of gravity and the pump, push the water through the filter media, and then back into the tank. 

This is made possible through the canister filter’s extremely strong and durable electric pump.

How Do I Set Up a Canister Filter?

The set up of a canister filter is relatively easy. Begin with setting up the outside canister, trays, and washed filter media in the desired place beneath or next to your aquarium. 

Determine the length to cut down the intake and outtake tubes if needed, and connect the tubes to your canister. 

After choosing between the spray bar or nozzle, attach the intake and outtake tube to the side of your aquarium using the suction cups provided. 

When this is complete, you have successfully done the basic setup for a canister filter.

How Do I Start a Canister Filter?

In order to get the filter completely functional, you must do something called “priming” the filter, which just means to fill the vessel with water to give it a kickstart. 

This can be done in several ways and depends on how what works best for you. 

It is important to remember to prime the filter because the pump is not meant to run with just air and can be damaging to the canister filter’s functionality.

Fill the Canister with Water Before Putting the Pump On

While you are filling the canister with filter media and its trays, you can choose to fill the canister up to 60-70% of the way. 

If you try to attach the top of the canister (the pump) and water overflows, there is too much water in the canister and it needs to be poured out. 

Forcing the pump on when there is too much water will cause an air bubble, and cause the filter not to work.

Rapidly Press the Priming Button.

On your canister filter’s pump, there is a large button that can be pressed to manually pump water into the intake tube. 

This is another way of priming but can be time-consuming. 

Even when you fill the canister up halfway with water, the priming button is often needed to get the filter up and running before plugging it in. 

Immediately after pressing the priming button rapidly while making sure water is coming into the intake tube, plug in the filter.

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