Fluval Filter Not Working After Cleaning [Reason +Solution]

Every aquarist has experienced that the tank water Can get dirty so fast. No matter how many fish species you have, the one thing that should be up and running at all times is your Fluval filter. The filter not only cleans the waste generated in the tank, it also adds oxygen which is very important for the fish.

Remember that even if you do all the necessary things to keep your tank water clean for the fish, without having a proper filtration system, it will all go in vain. Imagine you have a perfectly working filter but after you clean it, the fluval filter stops working. This is a disaster situation and trust me I’ve been through this many times over the years. 

In this article, I have tried to write about what things can go wrong after cleaning a fluval filter and how you can get it started without much of a hassle. Besides, at the end of the article, you will find a complete checklist to get your fluval filter working. So, without making any delay let’s get started–

Why Is My Fluval Filter Not Working?  

1. The Filter Is Clogged

A popular misconception is that only passing it under running water for a few minutes can clean the Fluval filter. Mostly, a thorough cleaning requires more detailed wiping and scrubbing with a brush. Sometimes even after that, the internal parts like the intakes and motors of the filter can still be clogged. 

You see, proper cleaning means disassembling all the parts of the filter and cleaning it thoroughly with a clean cloth or a soft brush. So it is very important to do a thorough cleaning every couple of weeks to prevent the filter from clogging. 

Look closely and make sure there is nothing blocking the intake pathways. But if you find anything, use the force of water or any small stick to remove it from there. 

2. The Flow Rate Is Not Adjusted

Another problem that occurs very frequently is when the filter is cleaned and changed, its flow rate is not properly adjusted. As a result, the fluval filter stops working functionally. 

After cleaning, the adjustment of the flow rate is very crucial because an incorrect rate will not make the filter able to clean the water and it will rather make the tank water stagnant. You can manually adjust the flow rate according to your tank’s demand. 

However, some filters come with an automated flow rate so there’s nothing you can do to control the flow as It will adjust the flow on its own. But if it seems to malfunction, you have to get a new filter for your tank.

3. The Power System Broke Down

Sometimes there is no clogged intake and the flow rate is also adjusted but the filter is still not working. This may be due to any electrical issue inside the filter. Check if both the outlet and the filter power button are turned on at the same time. 

Also, make sure the extension cords are working. Sometimes the filter is perfectly functioning but the extension cord has gone bad and fails to supply the electricity. In this case, getting a new extension cord is the best option for you.

4. There Are Leaks In The Canister

While you are checking your filter intake make sure the canister is properly sealed because if there are any leaks inside it the filter will not be able to pump any water. Even if the filter keeps working the flow of water will be too slow. 

First, check if the seal ring is cracked or broken. If the seal ring is dry but there is no lubrication you can apply some silicone lubricant. However, refrain from using other lubricating materials at any cost such as Vaseline. Because it will lead to more leakages and will break the seal as well.

Then, close the canister lid and make sure it has been placed in the proper position. But there can also be leaks in the intake hose. This issue mostly goes unnoticed because the holes are usually very tiny and irregular. In this case, consider replacing the filter intake hose and the canister.

5. The Impeller Is Broken

When the impeller is broken the filter loses its ability to suction the dirty water. As a result, the fluval filter stops working. In this situation, resetting the impeller will be the best option for you. But if that doesn’t work, you can also check the manual that came with the filter to check how to repair the impeller. 

If there is no such option you can replace it easily with a perfectly working Fluval impeller. However, even after checking all of the above if nothing seems to work then the best thing to do is replace the fluval filter entirely with an upgraded one.

The Additional Checklist To Start The Fluval Filter 

  • If the intake hose or outtake hose is much longer and looped up somewhere, the filter won’t start. So, try to keep the intake hose below the water level and the outtake house above the water level to facilitate the whole system.
  • Clear any blockage present in the intake hose and make sure there is no bubbler around the intake hose as well.
  • Prime the filter with the help of an instant prime button. Make sure to unplug the power cord from the outlet before that. When you hear the water is flowing inside the canister you can stop pressing the button. When the canister is full of water you can plug back your filter in the outlet. 
  • See if the filter media is clean enough because if it’s too dirty it will not allow the water to flow through its surface and as a result, the aquarium water will stay dirty.
  • Check if the model of your fluval filter is appropriate for your tank. Sometimes the wrong sized filter in a big tank can be dysfunctional. Get the right model according to the weight by measuring the capacity (gallon) of your tank.

Frequently Asked Questions (FAQs)

What Happens If The Fish Tank Filter Stops Working?

If a fish tank filter stops working, the water will be contaminated with harmful toxins produced from the fish waste. This will sadly result in the fish and snails becoming sick or they can be dying within a couple of days if the situation is not handled immediately. This is why, whenever the aquarium filter is not working an immediate step needs to be taken by either repairing or replacing it.

How Long Can Fish Survive Without a Filter Running?

Well, it depends on several factors. If the tank is overcrowded then it will run out of oxygen pretty quickly and harmful toxins will take over the entire aquarium. In this situation, the fish can survive only a couple of days. But if the tank is not heavily stocked then the rate of toxin production will not be much high and the fish may be able to survive a couple of weeks without the filter running. 

Why is My Fish Tank Filter Not Blowing Bubbles?

Bubbles are beneficial for the fish as they introduce more oxygen to the water. So, If you have a fish tank filter that is not blowing bubbles check if the filter is properly installed. Besides, check the connection of all the hoses and clear any blockages present. Also, some filters need to be primed before starting so this could also be a reason why it’s not blowing bubbles. 


Cleaning the tank filter regularly is one of the most important tasks for every aquarium keeper. But sadly, in some cases, the fluval filter stops working after you clean it. This situation can be easily handled if you know where to look for the issues. 

Make sure to reassemble the filter properly after you clean it and connect all the hoses in the right place. And don’t forget to make sure the filter is well connected to the electrical outlet.  If it still does not start then you can take the help of this article to get to the bottom of this situation. 

I have dealt with this issue a lot so I know the frustration when the filter is not working after cleaning it. So, whenever your filter stops working make sure you keep this article within your reach so you can get your fluval filter up and running within a short time.

Howard Parker

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