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Fish Tank Filter Not Working? 3 Reasons & Fixes

Lindsey Stanton Profile Picture

By Lindsey Stanton

fish tank filter pip and little fish

There is probably nothing more important in your fish tank setup than the filter. The filter is what keeps the water clean, keeps the bad bacteria at bay, helps to oxygenate the water, and filters out toxins, chemicals, and unwanted compounds. It is something that every fish tank absolutely needs to have, and without it, not only will the water in your aquarium be very dirty, but your fish may actually die.

For this reason, we want to talk about a fish tank filter not working, why it is not working, and what you can do to fix it. Let’s get right to it and talk about some of the most common fish tank filter problems out there.

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The 3 Potential Reasons Why Your Fish Tank Filter Is Not Working:

Let’s look at the 3 common issues that affect filters, how to diagnose the issue, and lastly, the solution to fix it:

1. It Just Won’t Run or Simply Won’t Turn On

Something that many people experience when it comes to their fish tank filters is that the filter just won’t run or simply won’t turn on. This can be due to a number of different reasons. One of the biggest causes of a fish tank filter that just won’t run is a clogged motor. This is much like our second point, which has to do with a clogged impeller, intake, or outtake tube, but in this case, something might be stuck in the motor.

A clogged intake or impeller will still try to suck in water but will only make noise and actually do nothing, whereas a filter with a clogged motor won’t turn on at all. The solution to a clogged motor is fairly simple. Just open up the filter, take it apart piece by piece, and unclog it. If you need to, you can use your hands, use lightly compressed air, or if the motor itself is waterproof, just blast some water through the motor.

Another cause of a completely silent and not working filter is a power surge, which may have happened in your home. A power surge may cause the filter to give out and may only require you to wait for a few hours before turning it back on. However, a power surge may also completely fry the filter and force you to get replacement parts or a whole new filter.

There could also be an issue with the power source or the connective cables. There might be a blown fuse, a tripped breaker, a broken cord, or broken wires, most of which can be easily repaired or replaced. If none of these things are the problem, then the most likely issue is the motor itself.

We aren’t mechanics and, likely, neither are you, but if the motor itself is the problem, you can always buy repair kits. Keep in mind that the extent of the damage will determine how expensive it is to fix the motor and the filter in general, so if there is too much to be done, it may just be cheaper to spring for a brand new filter, most likely not the one that just broke though (this one is a good option).

filter Shutterstock
Credit: underworld, Shutterstock

2. Loss of Suction or No Suction at All

One of the most common problems that people experience with their fish tank filters is that there is a loss of suction or no suction at all. You see, a fish tank motor run an impeller that serves to suck water from your fish tank into the intake tube, through the filter media, and back out the other side in the form of perfectly clean water.

The most common issue when there is no suction in the filter is that there is a clog somewhere along the line. If you can hear the filter motor running but you can see no visible suction, then chances are that you have got yourself a clogged intake tube, impeller, or outtake tube. Luckily, this is a problem that is solved fairly easily.

All you really need to do is to completely take the filter apart piece by piece until all possible parts are disconnected. Search for the clog with your eyes and if you see it, remove it. You can also try using water from your sink to flush it out.

Whatever method of unclogging you use, make sure to get everything out of the filter because if you don’t do it right the first time, you will just have to do it again. This is an especially big problem for people who use sand as substrate because it has a tendency to bunch up and jam filters, which is also true for people who use small pebbles or very small rocks, as one of them is often more than enough to cause a severe clog.

If nothing works, then you probably have a busted filter and will most likely need to order replacement parts or replace the filter all together.

Credit: RobinsonThomas, Shutterstock

3. Improper Flow Rate

Another pretty serious problem that many people experience with their fish tank filters is an improper flow rate. Now, this is not actually a problem with the filter itself, but it does affect your fish. You see, different fish need different water flow rates, with some liking a heavy flow to swim against and some that can’t handle fast-flowing water and just get swept around the tank.

This is more or less a problem that you can only solve by buying the right filter. Your best bet is to get a filter with an adjustable flow rate. If your filter is not adjustable and is too powerful or is not powerful enough, the only real solution is to buy a different filter that will accommodate the needs of your fish.

colorful cichlids swimming in tank
Image: andreibucataru.ro, Shutterstock

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Whatever the case may be, and whatever the solution to your fish tank filter problem is, you need to take care of it as soon as possible. Without proper filtration, your water will suffer from a buildup of waste, chemicals, and toxins. Plus, it won’t be properly oxygenated either, all things which can rather quickly lead to the unfortunate demise of your fish.

Feature Image Credit: mariait, Shutterstock

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