HomeSea LifeFish KeepingAquariumsTop Fin › Filter Won't Work

Troubleshooting Top Fin Filter Function

For the most part, Top Fin® starter fish tanks include a filter as part of the normal assembly. But, you can also buy various types of power filters and cartridges to improve the removal of harmful contaminants and waste.

So, what happens if your filter stops filtering and the water is getting cloudy? This section contains a list of reasons why a Top Fin filter may not be working efficiently and how to troubleshoot the most common fixes.

Reasons Why Top Fin® Filters Stop Working

No matter which Top Fin aquarium brand you have, the recommended devices that help you keep the water clean include:

Pro Tip: Use replacement parts and cartridges for easier maintenance.

If you are learning how to care for fish in an aquarium, the filter is a device that cleans the water and improves the general health of fishes kept in captivity.

Even so, there are times when aquarium filters stop working, or don't function efficiently, and you want to find out why. In most cases, the reason that it's not pumping will be a problem with the power supply, a blocked filter, or a faulty impeller.

So, this section will help if you're troubleshooting a water filtration problem and need to determine "why is my Top Fin® fish tank filter not working properly"?

1. Is the Aquarium Power Filter Clogged?

On many occasions, a clogged aquarium filter assembly will be the root cause of the problem. This is a good place to start troubleshooting if it is making unusual noises or it has stopped working altogether (e.g. it's not circulating the water around the tank).

So, why do fish tank filters get clogged in the first place? In general, it could mean that you are not cleaning it as often as you should.

Nonetheless, you also want to make sure that it is big enough for the job in hand. In fact, having a filter that is too small for the size of the container is one of the common mistakes beginner fish keepers make.


Simply put, the filter will be filling up with waste products (e.g. physical and soluble chemicals) too quickly. Hence, having to strain high quantities of substances is likely to overload the device.

Note: Remember to clean or replace the Top Fin® filter at regular periods. The general recommendation is to replace the filter cartridge every three (3) weeks and clean the filter assembly at least once a month.

The Best Way to Clean a Top Fin Filter

There are several important things to be aware of before you start cleaning the filter. There will be some beneficial bacteria living in the aquarium and inside the filter. Thus, it is best not to harm them.

So, you should avoid using cold tap water during the cleaning process. Instead, you can either use water from the fish tank to clean the parts or water that is already at room temperature (e.g. previously prepared in a bucket or similar).

Here's the thing:

Be sure to unplug the power filter from the mains supply and then take it out of the aquarium. Clean the assembly in a bucket that contains room temperature water and a conditioner.

Next, go ahead and disassemble the main parts of the power filter, such as the cartridge, basket assembly, and the pump. Most of the filter media will be plastic, so it should be easy to remove any debris that is clogging the normal flow rate.

Why is My Top Fin Power Filter Not Working? List of Causes and Solutions.Remember, it's best to leave some of the good bacteria on the plastic parts so that they can start to grow again. Thus, try to avoid using a stiff brush when you clean the filter media.

Next, use a brush or sponge to rinse debris and algae away from the non-media parts - in warm water (not too hot).

When you have finished cleaning all of the parts and media, reassemble them and place them back inside the aquarium. Turn on the power supply and test for proper function.

Replacing a Top Fin Fish Filter Cartridge

What if your Top Fin filter is still not working after cleaning it? If this is the case, you may need to replace the cartridge.

Turn off the filter and unplug it from the power supply. Then, adjust the flow rate button to the minimum setting and open the cover.

Remove the dirty cartridge (dispose of it in a safe manner) and pour out the cloudy water from the filter box. But, before you insert a new filter cartridge, rinse it with cool water to remove any debris and dust particles. Then, put it inside the opening and top up the filter with clean water as necessary.

Pro Tip: The cartridge replacement indicator is blue in the normal condition. It will turn red when the cartridge is blocked and needs replacing. The tab on the cartridge should be in the upward position when you install it. Finally, adjust the flow rate to the maximum position and check for proper function.

2. Issues with the Power Supply

What if the filter fails to pump water or the normal flow has stopped altogether? First, check that the power outlet is functioning as it should. Unplug the electrical cord for a moment and reconnect it to the power source. Check to see if the impeller starts working.

Other common power supply issues can include:

One way to check whether the connectors are in good working order is plugging the filter into an alternative power outlet.

3. Problems with Aquarium Filter Impellers

One of the main components for efficient fish tank filtration is the impeller. In fact, it is the main part that helps to circulate and recycle dirty water into clean water. In other words, a broken or blocked impeller (e.g. with gravel or substrate) could be the reason why a Top Fin filter stops working.

After checking the impeller for loose or broken rotor blades, make sure it is clean and free from waste. You should always replace a damaged impeller housing according to the manufacturer's specifications.

Improper or Irregular Water Flow

Having a fish filter with the incorrect capacity for the size of the aquarium that you have (e.g. too small) will often lead to irregular and improper water flow.

Thus, the best power filter for a fish tank is one with the correct size and capacity for the specific size of container that you are using. The same principle relates to glass and plastic aquariums - especially with starter kits.

Important: Make sure you submerge the filter deep enough into the tank as recommended by the manufacturer.

4. Why is My Aquarium Filter Not Making Bubbles?

There are a few easy fixes to try if your filter has suddenly stopped blowing bubbles. So, check to see if you have a dirty or clogged filter and clean where necessary (see above).

Another solution to the problem could be that someone unplugged the air pump from the regular power supply - or someone nudged it and it became loose.

Some serious issues could include a damaged or faulty rubber membrane, kinked or cracked water inlet tubing, or inappropriate pump placement (e.g. tilting away from the tank).

Related Information and Help Guides

Pro Tip: The short video tutorial [6:41 seconds] presented by 'More Palmer Aquatics' explains some simple fixes and adjustments to try when a hang-on-the-back aquarium filter stops working.

Divers also enjoyed reading about...