How to Troubleshoot a Fish Tank Filter that Refuses to Turn on?

Your fish tank filter can stop functioning suddenly without warning. In particular, the fish tank won’t cycle if the filter won’t turn on. Both new and old filters may be affected by this problem.

But, what are the causes of this issue? Additionally, how do you troubleshoot a fish tank filter won’t turn on?

To fix the problem, first of all, you have to inspect the water flow. Then, take off the hose and clean it. Afterward, clean all of the components of the filter using water from the tank. Lastly, prime the filter and fix any leaks or bent hoses.

If you want a detailed guide on the troubleshooting method for a fish tank filter that won’t turn on, keep reading.

What Causes the Fish Tank Filter that Refuses to Turn on?

Most fish tank filters that won’t turn on have a few common causes for this. The main causes include failure to prime the filter, hose and canister leaks, blockages, and electrical issues.

Hose bends, a filthy cartridge, a damaged impeller assembly, a damaged motor, broken impellers, and many more are additional typical reasons.

Replace any damaged or defective parts if you have any. Follow the problem-solving strategies I’ve described below for the other causes.

5 Steps to Troubleshoot a Fish Tank Filter Won’t Turn On: 

A fish tank filter not turning on is one of the most common problems users face. But most of the time, they tend to replace the filter without even troubleshooting it.

But there are many possible solutions to this problem. You may find many of these solutions on the internet but most of them are not dependable.

So, I will provide you some quick and simple troubleshooting methods that you can easily perform on your own.

Things required to troubleshoot the fish tank filter won’t turn on:

Examine the following list of equipment and materials required for troubleshooting a fish tank filter:

Hose cleanerImpeller (if needed)
SpongesHoses (if needed)
BrushesCeramic shaft (if needed)
Small brushesMotor (if needed)
BucketsFish tank water test kit

Step 1 – Inspect the Fish Tank Water:

You should check the water daily for movements of plants or decorations inside to make sure that the filter is on.

 Fish Tank
Fish Tank

You can also put your hand inside the water or in front of the filter to examine the flow.

 Fish Tank
Fish Tank

Step 2 – Clean the Fish Tank Filter Hose:

First of all, turn off the power and disconnect the plug. Now, detach the hose connector block.

 the hose connector block.
the hose connector block.

Now, detach the inflow pipe from the fish tank.

detach the inflow pipe from the fish tank.
the inflow pipe

Afterwards, detach them from the connector block.

 the connector block.
the connector block.

Now, you should use a hose cleaning pipe to clean it.

Put the string of the pipe
Put the string of the pipe

Put the string of the pipe through one end and take it out from the other end. Now, put water inside the tube. After filling it, pull on the string and spin it while pulling it out.

Step 3 – Cleaning the Filter:

Now, you have to clean the media using fish tank water, a sponge, and a brush. Put the water inside a bucket

Put the water inside a bucket
Put the water inside a bucket

Now, clean the sponges inside the water. After that, you have to take out the shaft and the impeller.

If the shaft is made of ceramic, it may break. If it is broken, you have to replace it.

If it is broken
If it is broken

Clean them using water from the fish tank. Also, clean the part where the impeller sits on.  If the impeller is broken, you should buy a new one or install a spare impeller for a replacement. Finally, put every part back to place.

Step 4 – Priming the Filter:

Take the outflow hose and put a bucket underneath it. Now, suck on the end of the hose and let the water flow for 20 seconds into the bucket.

Priming the Filter
Priming the Filter

Now, connect the outflow hose to the outflow pipe.

Step 5 – Fix the Hose and Leaks:

Inspect and fix if there are any loops on the inflow or outflow hose. Also, adjust the length of the hose.

Now, ensure that the canister is closed and no leaks are visible. You might also need to change the hoses.


  1. Turn off the filter and pull out the cable from the outlet before fixing it.
  2. To get rid of the airlock in the impeller, prime the filter properly.
  3. If you hear a noise, the motor might be malfunctioning. Bump the impeller and replace or repair the motor.
  4. Do not hesitate to send in the fish tank filter for warranty servicing if you fail to fix it yourself.
  5. Check the level of ammonia, nitrate, and nitrite in the water. If the level is high (above 15-20 ppm), it is an indication of a failed fish tank filter.
  6. Before turning your filter on after cleaning it, put it inside the water before turning it on.
  7. Make sure that the wires, plug, and outlet are connected properly and have electricity flowing through the filter wires.

Frequently Asked Questions (FAQs)

How frequently should I clean the fish tank filter?

If you own a canister filter, clean it every three months. Clean the sponge filter twice a month and clean the hang-on and in-tank filters at least once each month.

Do I need to manually prime the fish tank filter?

Some fish tank filters prime automatically and you need to press a button to prime it. But cheap filters do not have this feature. You have to prime these filters on your own.

What will happen if I do not use a filter in my fish tank?

If you do not install a filter, the water will become dirty due to low or no filtration. Also, a high amount of toxins, ammonia, nitrite, and nitrate will build up inside the water which may be harmful to the fish.
Also, if you do not have an air pump installed, a filter failure may result in a low amount of oxygen inside the fish tank.

What should I do if my fish tank filter has low water flow?

Clean the sponge and filter media. Also, remove any blockage from the intake hose. Check the connections and tighten them if there are any water leaks from any joins.

How do I know when the fish tank filter has stopped working?

First of all, inspect the water flow. Always check the nitrate levels and keep readings. If there are no suctions or sounds, it might indicate that the filter has stopped functioning.

How do I control the water flow rate of my fish tank filter?

If the filter you own does not feature a built-in water flow system, you can’t control it. If you want to control the water flow, buy a powerful and pricey filter.
The Aqua Clear Filter and the Aquael Ultramax Filter support a flow control system.

Final Verdict

You may experience difficulties with your fish tank filter at any time. But mostly, it is due to clogged and dirty filter parts. If you manage to clean it properly, the filter will start to work again most of the time.

If the filter of your fish tank fails to operate, the health of your fish might be in danger due to high amounts of toxins and lack of oxygen.

I have included the troubleshooting method for fixing the issue when the fish tank filter won’t turn on. Follow the instruction properly to get the best result.

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Arif H Fahim

Welcome to PetFishTank! My name is Arif. I make an effort to publish educational articles using my many years of expertise as a fish owner.

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