How to Prime an Aquarium Filter Pump

An aquarium filter is an essential component of a healthy and thriving aquarium. It helps to maintain a clean and safe environment for your fish and other aquatic creatures.

To function effectively, a filter’s pump must be primed. Priming a filter pump involves filling it with water, which creates suction and allows the pump to work efficiently.

If the pump is not primed correctly, it may not work at all, which can be dangerous for the fish. But today, I am here to share with you everything you need to know about how to prime an aquarium filter pump.

PS: Don’t forget, once you’re done reading this article, to check my previous article about the best filters for your tank.

Why is priming necessary for a filter pump?

Priming is a fancy way of saying we’re getting the pump ready to do its job – moving water. However, it’s a crucial step because pumps are designed to move water, not air.

primed water filter pump

If there’s air trapped in the pump or the tubes, your pump can run dry, which can cause it to overheat and possibly fail. That’s a big no-no! We don’t want to fry our pumps like fish sticks, do we?

This means that priming is necessary to ensure that the filter pump is working effectively. Now, depending on the type of filter you’re using (HOB filter, canister or powerhead), you will do things slightly differently. We’ll go over each down below.

How to prime a hang-on-back (HOB) filter pump

The HOB filter is a popular choice for many aquarists due to its ease of installation and maintenance. Also, the filter pump is really easy to prime too.

Here’s how to prime it:

  1. First, make sure the filter is securely hanging on the back of your tank.
  2. Fill the aquarium until the water level is above the intake tube of the filter.
  3. Pour water directly into the filter box until it’s nearly full.
  4. Now, plug in the filter. It should start pulling water from the tank into the filter and pouring it back into the tank.
  5. Watch out for bubbles coming out of the outflow. This is air being pushed out. Once the bubbles stop, your HOB filter is primed and ready to go!

How to prime a canister filter pump

Canister filters are a bit more complex, but they’re a favorite among fishkeepers who need heavy-duty filtration (or have large tanks).

Here’s your step-by-step guide to priming a canister filter:

  1. Start by assembling the canister filter following the manufacturer’s instructions.
  2. Fill the canister with aquarium water. This is crucial because the filter needs water to start the siphoning process.
  3. Attach the intake and outflow tubes, ensuring they are securely fitted.
  4. Open the valves to allow water to flow into the intake tube.
  5. Plug in the filter. The pump should start moving water from the tank, through the canister, and back into the tank.
  6. Once the water flows smoothly without any bubbles, you’re done! Your canister filter is primed and ready to work its magic!

Canister filters are great filters for large aquariums. Make sure to read my article sharing the best ones for large aquariums, to make sure you’re doing everything right.

How to prime a powerhead filter pump

Priming a powerhead filter pump is similar to priming an HOB filter pump. Here’s how to do it:

  1. Fill the powerhead with water until it’s almost full.
  2. Hold the powerhead over the aquarium and slowly lower it into the water.
  3. Wait for the bubbles to stop coming out of the powerhead and for water to start flowing through the outflow tube.
  4. Turn on the powerhead and check for leaks.

Troubleshooting tips

If you’re having trouble priming your filter pump, here are a few troubleshooting tips:

  • Check that the intake tube is not clogged or blocked.
  • Make sure the valves on a canister filter are closed before turning on the pump.
  • Make sure the powerhead or HOB filter is properly attached to the aquarium glass or rim.
  • Try filling the filter pump with water from a bucket rather than from the aquarium.

If none of these tips work, refer to the manufacturer’s instructions for troubleshooting specific to your filter pump.

Safety precautions

When working with a filter pump, it’s important to take safety precautions to avoid injuring yourself or damaging your aquarium. Here are a few key safety tips to keep in mind:

  • Always unplug the filter pump before priming or performing maintenance.
  • Use caution when handling the filter pump and avoid touching the impeller, which can cause injury or damage to the pump.
  • Make sure the aquarium is properly supported and the stand is strong enough to hold the weight of the water and the aquarium equipment.


Now here are a few questions that you might have regarding the entire process of priming your aquarium’s filter pump:

Can I use tap water to prime my filter pump?

Yes, you can use tap water to prime your filter pump. However, it’s recommended to use dechlorinated water instead as some chlorine might remain in the pump and cause trouble in the aquarium.

Alternately, wait some 24 hours after using tap water to prime your filter’s pump to allow the chlorine to evaporate.

How often should I prime my filter pump?

You should prime your filter pump whenever you perform maintenance or after a power outage or disruption to the filter’s operation.

Can I prime my filter pump with my fish inside?

It’s not recommended to prime your filter pump with your fish, as it can be stressful and harmful to their health. It’s best to remove them temporarily during the priming process.


Priming an aquarium filter pump is an essential step to ensure that your filter is working efficiently.

By following the steps outlined in this article, you can easily prime your filter pump and keep your aquarium clean and healthy for your aquatic inhabitants.

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