How to Prime An External Canister Fish Tank Filter Pump

By Eddie Waithaka @aquariawise

How to Prime An External Canister Fish Tank Filter Pump

Fish tank filter pumps are essential to any aquarium setup. They clean out dirt from the tank and keep the water from turning toxic to fish.

Aquarium filter pumps come in varying designs, but for the most part, they work the same way. They pull water from the fish tank, pass it through a filter media to trap out the dirt, then pump the water back into the fish tank.

That said,…

Your fish tank filter will not operate if the tubings are filled with air (instead of water) hence the need to prime it the first time you use it or after cleaning or a power outage.

To start the prime in your fish tank filter, attach the inlet hose to the unit with the other end inside the tank and filter media set in place. Attach the outlet hose to the filter, then suck on it to get the water flowing into the filter unit. Once the canister is full of water, place the outlet inside the tank, plug it in, and start the pump.

If your filter is self-priming, you may not need to suck on the outlet tube with your mouth. A priming button should start the process automatically.

Your canister filter should prime and start cleaning your fish tank if all hoses and canister body are full of water, filter is clogged or the impeller is jammed.

What Does Priming A Filter Pump Mean

Priming a fish tank filter means filling the hoses and canister with water to get it going. The process should expel air from the system and allow water to flow through the unit freely.

Most filter makers position the pump inside the canister lid, and plugging in the unit won’t pull the needed water into the reservoir. You will need to start the process by sucking on the outlet.

Ensure you do not start your fish tank filter pump before priming it to avoid damaging the impeller.

Do You Need to Prime Your Fish Tank Filter

You need to prime your fish tank filter before you plug and start it to remove air from the hoses and reservoir. Failing to prime the filter may damage the impeller, causing the unit to operate below the design capacity or fail to start.

When you plug and start a filter unit without priming it, you will most likely hear the buzz of the filter motor running, but there will be no flow in or out of the filter until you add water into the system.

Even so,…

Not all aquarium filters need manual priming (by sucking on the outlet hose). Some come with a primer button that will automatically start the prime.

Do You Need to Prime A Canister Fish Tank Filter

A canister filter needs priming to ensure water and not air in the hoses and reservoir before it starts. The idea is to have as much water flowing from the tank into the filter for cleaning, which is unattainable with air pockets in the system.

By design, most canister filter units will not start without water and may even damage the impeller if you try to plug it in.

Do You Prime A Canister Filter Before Plugging it In

You should prime your canister filter before plugging it in to remove any air in the system. Failure to prime your may cause a failed start or damage to the impeller.

Trapped air has to be removed from a canister filter to effectively clean the water, which can only be achieved by priming your unit.

How to Prime An External Canister Fish Tank Filter

To prime newer self-priming models of canister fish tank filters, you only need to press the provided prime button to start the process.

However, if you have an older filter, you may need to start the priming by sucking on the outlet hose, which will create a flow from the tank to the filter, and once the reservoir and pipe are filled, plug and start the unit.

You can use a submersible pump to start the suction if you have it at home.

If you are not ok sucking on the outlet to start the flow (and don’t have a pump), unscrew the cap on the intake pipe and fill the hose with water. Lower one end, latch it on the filter and place the other into the tank to start a siphon.

The siphon will pull water into the filter canister through the intake and blow air out of the return pipe until the filter is filled and primed.

If any of these hacks does not work for you,…

You can manually fill your filter canister as much as possible, assemble and submerge the intake and outlet hoses in the tank, and plug in the filter. Tilt the canister to the side to submerge the impeller and start the unit.

Let the filter run for a minute while tilted before you level it. If it does not start, add water to the canister and restart the process.

How Do You Start A Fish Tank Filter

To start a new fish tank canister filter, prime it by adding water in the filter reservoir and hoses to expel any air in the system before you plug it into a power outlet. Once the filter is fully primed, connect it to a power source and turn it on.

Start new filters with old water from the fish tank to help beneficial bacteria from the aquarium establish in the filter media.

To start a filter in a new tank setup, you can use tap water with a conditioner to prime your filter.

The filter motor should make a buzzing noise when you start it. Then the water should flow from the tank through the filter inlet into the tank reservoir, then out of the outlet hose into the tank.

If you install a spray bar on the outlet, the water should make a splash or low waterfall noise as it drains back into the fish tank.

How to Get Trapped Air Out of An External Canister Filter

To get trapped air out of an external fish tank filter, fill the pipes and canister with water from your fish tank. Place the inlet tube inside your fish tank, then suck on the outlet end to start the flow.

Air in the filter will be displaced from the system and go out through the outlet pipe. After you suck and place the outlet hose in your fish tank, you will notice air coming from the tip and forming bubbles in the water.

Wait until all the trapped air is expelled and the canister is filled with water before you plug and start your filter.


That’s all for this post.

All the best with your finnies🐟🐡🐠.

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