Why Is My Fish Tank Filter Not Working? Common Problems & Fixes

The role of filters for aquariums is probably well known to everyone. It always works hard to keep your aquarium healthy.

Once your filter wants to “strike” it will be a big problem for your aquarium. So you need to know how to fix the problems of the filter system to promptly rescue your fish.

Accurately diagnosing what’s going on will help you shorten your troubleshooting time. And of course, there are many possible causes for your aquarium filter to fail. So you need to learn to know Why the Fish Tank Filter Not Working? And how to handle it.

The importance of an aquarium filter

Habitat plays a very important role in the development of aquarium fish. For the best quality of water and habitat for aquarium fish, suitable aquarium filters are indispensable.

There are many different types of aquarium filters, but they all have a common purpose of making sure the aquarium is always in good working order. The following roles demonstrate the importance of an aquarium filter:

  • Filters out dirt, debris, and toxins.
  • Keep the water in the tank clean at all times.
  • Provide more oxygen to the water.
  • Minimize algae growth in the aquarium.
  • Creates water circulation in the aquarium.

Signs Your Aquarium Filter is Not Working

Why Is My Fish Tank Filter Not Working? Common Problems & Fixes

In the process of caring for and admiring your fish, problems with your aquarium filter can happen at any time.

No matter what the problem is, serious or not serious. You must first detect it in time, then consider finding solutions.

Here are some telltale signs when an aquarium filter isn’t working or isn’t working properly:

The concentration of Ammonia and Nitrate in the water increases

If you feel that the water in your aquarium is not being cleaned in an unusual way. Use measuring devices to check the amount of Ammonia and Nitrate in the water. If the water in your tank has too high a concentration of Ammonia and Nitrate then chances are your aquarium filter is not working or not working properly.

No Suction

The filter inlet is located in a position normally visible to you. If your filter is working properly, you can easily see the water being sucked in. When you don’t see that in the inlet position, your filter is not working.

No sound or abnormal sound

A filter in operation will make different noises big or small, but it is already attached to you in the process of taking care of the aquarium.

If you notice that the noise disappears or is strange, it is most likely a sign that your aquarium filter is having a problem.

Why Is My Fish Tank Filter Not Working? Common Problems & Fixes

Fish Tank Filter Not Working? 3 Common Reasons

It Just Won’t Run

This is something that many people have encountered in the process of playing with aquarium fish. So don’t worry when suddenly one day your aquarium filter suddenly stops working. Your filter stops working for many reasons, like:

The filter is not powered

The sudden increase in voltage

The fan blade is clogged, stuck

Engine failure or fire

As mentioned above, you can easily tell your aquarium filter is not working at first because the suction head does not form a flow and there is no sound coming from the device. After a while, the concentration of Ammonia and Nitrate will increase.


To be able to fix the filter not working, we must find out why the aquarium filter is not working. We perform the test by following these steps:

Step 1: Check the power supply status for the filter

First, check if the plugs are loose or unplugged. Are the connection wires broken or open? This is a very common problem, especially for families with more pets such as dogs and cats.

They are very mischievous and run all over your house, most likely getting entangled in the power cord and unplugging the power plug. If you found the reason your filter stopped working at this first step, congratulations! You will fix it easily.

Step 2: Check for clogging of the motor propeller

When the filter has a stuck impeller, it will not be able to rotate, so there will be no noise either. Unplug the power, then remove your filter from the aquarium. Open the filter and look for obstructions that interfere with the movement of the propeller.

If so, take them out and clean the filter again. With non-removable filters, you can check by blowing with compressed air or water to push out blockages if any. After cleaning the inside of the filter, put the filter back in the aquarium and power it up. If it works properly again then your problem is solved. If not, continue to check the next step.

Step 3: Check the engine

Here, it can be confirmed that the filter does not work because the engine is broken. Your job now is to determine the extent of the engine failure. You can consider repairing it according to your ability. Sometimes it’s more economical to buy a new filter.

No Suction

Why Is My Fish Tank Filter Not Working? Common Problems & Fixes

No suction is also a fairly common problem with aquarium filters.

In simple terms, the principle of operation of the filter is made as follows:

The filter uses a motor that powers the impeller, the impeller rotates to draw water from the tank into a tube, through the filter media, and then back into the tank.

In this problem only consider the case where the engine still rotates but does not draw water.

Because the problem of the motor not rotating was mentioned above.

Therefore, an aquarium filter that does not suck or sucks poorly can be due to the following reasons:

The filter inlet or outlet is obstructed

The filter media is too dirty

Impeller damaged or broken

This problem often occurs in aquariums that use a substrate of sand, gravel, or small rocks. They can easily get sucked into the filter causing clogging or damage to the impeller.


Step 1: Check for blockages at the intake and exhaust ports

Unplug the power cord and then remove the suction and discharge hoses from the filter.

Visually check for blockages inside the tube.

Perform removal if any and re-clean the parts.

Step 2: Check the filter media

During the filtration process, the filter media will retain the dirt, and debris to clean the water.

Over time, more and more dirt is trapped leading to them becoming clogged and water cannot pass through.

All you need to do is clean or replace the filter media. And make sure this will be done according to the specified cycle later.

If you feel the problem has been resolved in steps 1 and 2 then reinstall the filter in the aquarium and put it back to work to see if it is working properly. If you are not confident then continue to the next step.

Step 3: Check the propeller

To check the impeller, open the main compartment of the filter. If the propeller is found to be damaged, check to see if the propeller is replaceable. If it is replaceable then order and replace it, if not then consider buying a new filter.

Inappropriate flow rate

Inappropriate flow rate

The flow rate of the water generated by the filter is very important for the aquarium. That is why you need to pay attention to this issue as soon as you choose to buy the right filter for your small aquarium. There are fish that like to live in strong currents, but there are also species that are only suitable for a gentle stream. A flow rate mismatch problem is usually not due to a faulty filter but to the filter itself being unsuitable.


This problem will be solved very simply if your aquarium filter has a function to regulate the flow rate. You just need to adjust to the speed you want.

In case the flow rate is so high that your filter cannot self-regulate, you can place sponges at the intake and exhaust of the filter. This will help reduce the flow rate of your aquarium.

If the flow rate is too high, the filter cannot self-regulate. You should replace or add a suitable filter.

When to change your aquarium filter?

When to change your aquarium filter?

During use, there will be many times when your filter encounters problems. But luckily most of the problems you can fix immediately, however, depend on the quality of your filter. There are some situations where you should replace the filter with a new one instead of trying to repair it, like:

Engine failure

The motor is considered the heart of the filter. After testing, if you’ve determined the filter motor has been completely damaged or burned out, it’s time to get a new set of filters for your aquarium. You should only fix it when you are skilled in this area, otherwise, you will just waste time and money.

Your filter has an inappropriate flow rate

As noted above, an inappropriate flow rate can negatively affect the health of the fish in the tank. So once your filter has an inconsistent flow rate you have no measure to adjust. Don’t hesitate to buy another filter to replace, if the problem persists, maybe what you lose will be your fish.

Propeller is broken

In many types of filters, the impeller is a replaceable part when damaged. However, if your filter is among the rest or you cannot afford another propeller then you will have to consider purchasing a new filter for your aquarium. Do not try to replace it with a fan of a different filter because that will only waste your time.


Now, whatever the problem is with your filter, how to solve it is not something you worry about. The most important thing is that you need to detect the problem as soon as possible. That’s when your fish are in more danger than ever. Spend more time taking care of and observing your aquarium.

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