What to Do If Fish Tank Filter Stops Working: Complete Guide

What to Do If Fish Tank Filter Stops Working_ Complete Guide

Fish tank filters are one of the key components to cultivating a healthy environment for your fish. After all, they remove harmful toxins and increase the water quality of your fish tank. Like with anything, though, you may encounter some functional issues with your fish tank filter – and it’s essential to restore the functionality of your fish tank filter as soon as you can.

What should you do if my fish tank filter stops working? If your fish tank filter stops working, you should:

  • know how to tell when your fish tank filter isn’t working. 
  • diagnose and if possible solve the diagnosed problem of your fish tank filter
  • replace your fish tank filter if you can’t repair it.

To help you restore the functionality of your fish tank filter as soon as you can (and keep your fish healthy and happy), we’ve compiled a complete guide on what to do if your fish tank filter is acting, well… fishy. Let’s dive in.

What to Do If Your Fish Tank Filter Stops Working: the Complete Guide

Freshwater Filter Open

If you walk past your fish tank one day and notice it’s completely silent or not functioning as it should be, you might have a slight moment of panic. Your fish tank filter is what’s responsible for maintaining a safe and healthy environment for your fish – and you don’t want anything to happen to them!

While realizing your fish tank filter has stopped working can be panic-inducing, you shouldn’t fret too much. There are some common specific reasons for fish tank filters to stop working, and common fixes for those problems – and it usually doesn’t take a genius or a mechanic to try them.

Don’t go adding a new fish tank filter to your online shopping cart right away, or worse – begin planning any fish funerals. Below are several panic-dissolving steps you can take when your fish tank filter stops working. 

#1 – Know-How to Tell Your Fish Tank Filter Isn’t Working

Know-How to Tell Your Fish Tank Filter Is Not Working

Maybe you have a hunch your fish tank filter isn’t working, but you’re unsure. Perhaps you’re a new fish tank owner and want to make sure you know how to tell when your fish tank filter isn’t working in case it happens. No matter the reason, it’s important to know some of the telltale signs of a non-functional or less than functional fish tank filter. 

High Level of Ammonia and Nitrates in the Water

If you think your fish tank filter isn’t working – but want to be sure – you’ll be able to tell by the amount of ammonia and nitrates in your tank’s water. You’ll need a digital test or chemical test kit to check out the ammonia and nitrate levels in your water. If there’s an overly high level of ammonia and nitrates in your tank, then it’s highly likely that your filter isn’t working. 

No Suction

Fish tank filters need to be able to suck in water to begin the filtration process. Suction by your fish tank filter is often visible – and if you can’t visibly see any suction, you should assume your fish tank filter isn’t working. 

No Sounds – or the Wrong Sounds

Fish tank filters make noise, and the type of noise they make – or lack thereof – can be a reliable indicator of a non-functional filter. If your fish tank filter isn’t making any sound at all, you can assume it’s probably not working. On the other hand, if your filter is making a grinding sound, it’s highly likely that it’s not working correctly.

#2 – Diagnose the Problem and Try a Solution

If you think there’s a problem going on with your fish tank filter – or if it has just stopped working – you’ll first need to apply your sleuthing skills and try to diagnose the problem. By observing your fish tank filter, how it’s working (or not working), and its characteristics, you can diagnose the problem. Once you’ve diagnosed the problem, you can move on to troubleshooting options to try and fix it. 

Problem: No Suction

We mentioned that a fish tank filter with no suction is likely not working. As it turns out, loss of suction is a common issue with fish tank filters. Simply put, filters use parts called impellers and motors to operate. Impellers suck water from the tank into a tube, through the filter, and then back into the tank. The motor gives the impellers the power to carry out these functions.

When a fish tank filter has no suction, it could be because of a few reasons:

  • There’s a clog somewhere in the filter
  • The impellers are broken or damaged

Suction issues often arise in fish tanks with a lot of sand, pebbles, and small rocks. These objects often get sucked into the filter and create a clog. You’ll be able to tell that your filter isn’t suctioning correctly when you can’t see it at all.

Solution: No Suction

If you’ve determined that your fish tank filter has no suction, there are some simple steps you can take to try and fix the issue.

  1. Check to see if the motor is running. If the motor is not running, you’ll need to look into other solutions (below) and possibly consider buying a new filter unit. 
  2. If the motor is still running, but you have no suction, you could have a clogged impeller, intake tube, or outtake tube. You can continue to the following steps.
  3. Unplug the filter and take it apart – piece by piece – according to the manufacturer’s instructions. Make sure everything is disconnected. 
  4. Look for a clog. If you see any clogs, try to dislodge them and clean them out. 
  5. If you don’t see any clogs, clean and wipe all your filter parts and keep an eye out for a clog along the way.
  6. Put your filter back together, put it back in the water, and plug it in to see if suction has been restored (source)

Problem: Broken or Missing Impellers

When examining your fish tank filter upon realizing it has no suction, you may have noticed your filter has broken or missing impellers. Maybe you haven’t yet taken apart your fish tank filter, but suspect it could have broken or missing impellers. The impellers can be found by opening the main chamber of the filter.

Broken or missing impellers is a serious issue because the impellers are responsible for sucking in the water to push it through the filtration process. This issue is commonly characterized by a loss of suction, but may also be characterized by a grinding noise from the filter unit. 

Solution: Broken or Missing Impellers

If you’ve got broken or missing impellers, you should first check the owner’s manual and manufacturer’s instructions for your fish tank filter to see if your filter came with replacement impellers. If your filter came with replacement impellers, you can (and should) use those to restore the impellers to working condition. Don’t use replacement impellers from another filter.

No replacement impellers? Don’t fret – you can either order replacement impellers or look into purchasing a replacement fish tank filter. It depends on your preference, timeline, and budget. 

Problem: Flow Rate is Too High or Too Low

Flow rates are vital in fish tanks. Fish need to be able to have a flow rate that’s good enough to provide water movement, but not so strong that they can’t navigate the tank. Different filters have different flow rates, and not all filters have adjustable flow rates (although some do). Flow rate is often not a problem with the filter itself, but a problem of having the wrong filter. 

Solution: Flow Rate is Too High or too Low

If the flow rate of your fish tank filter is too high or too low, the solution is relatively simple and straight to the point.

  1. Check to see if your filter has an adjustable flow rate. If it does, adjust it up or down to your desired flow rate. 
  2. If your filter doesn’t have an adjustable flow rate, you’ll need to get one with the flow rate you need or a filter with an adjustable flow rate.
  3. If your flow rate is too low, you likely need to purchase either a more powerful filter or an additional filter to add to your setup. 

Problem: Filter Just Stopped Working

So, one day your fish tank filter just up and stopped working. You wouldn’t be the only one – it happens, and sometimes more often than you’d think. A fish tank filter can stop working for a wide variety of reasons, like:

  1. A power surge
  2. An issue with the connective cables
  3. A clogged motor
  4. A broken or burnt-out motor

As previously mentioned, you’ll know your fish tank filter has stopped working when there’s no suction or flow in the water, no sounds are coming from the unit at all, and/or there’s a high level of ammonia and nitrates in your tank. 

Solution: Filter Just Stopped Working

The solution to a fish tank filter that just stopped working will depend on why the filter just stopped working. You may have to try several troubleshooting options before finding out the proper solution. 

Before you try any troubleshooting options at all, make sure you unplug the filter. 

Next, try the following troubleshooting options. 

Look for Clogs

Take your fish tank filter apart just like mentioned above and search for clogs in the machinery. If you find a clog, clean it out, put your filter back together, and plug it back in. If it starts functioning again when it’s plugged back in, great! You’re probably in the clear. If not, move on to another troubleshooting method. 

Leave it Unplugged for a While

Try unplugging your fish tank filter and leaving it unplugged for a few hours. A power surge or electrical problem could have been the reason it wasn’t working. In that case, the filter could resume working when plugged back in after a while. If it doesn’t, you can try another method.

Check the Motor

Lastly, check the motor of your fish tank filter. Is it working at all? You’ll be able to tell by a slight noise and vibration from your filter. 

Note: you should only test the functionality of your filter’s motor while it’s in the water. Running the motor dry will cause it to break and stop working (if it hasn’t already). 

If your motor is working (but not properly) or not working at all, you can consider repairing the motor as per the manufacturer’s instructions. However, fish tank filter motors can be complex and tricky to restore, not recommended. If the motor of your fish tank filter is working improperly or has stopped working altogether, your safest bet is to replace your entire filter unit. This method is often less time consuming and more cost-effective, too (source)

Problem: Electrical Components

Issues with the electrical components of fish tank filters often arise. Electrical components, like the wires connecting the filter to a power source, the connecting pins, and even the power source itself can cause functionality problems. The electrical components of a fish tank filter can have issues because of situations like:

  • Unplugged wires
  • Damaged wires and pins
  • Power surge
  • Failed or turned off the power strip 
  • Failed or turned off electrical outlet 

Solution: Electrical Components

Thankfully, issues with electrical components are often easy to diagnose and easy to troubleshoot. 

Unplugged Wires

First, look for unplugged wires. Are all the wires plugged into the power source (power strip, electrical outlet, extension cord) and the fish tank filter? If not, you’ve got an easy fix – plug all the wires back into the appropriate places!

Damaged Wires and Pins

If that’s not the issue, check for damage. Did another pet get a hold of the wires and damage them? Have wires been cut or crimped? Is there any other damage? If there is damage to any of the electrical components, fix what you can, and replace what you can’t fix. 

Failed or Turned off Power Strips or Electrical Outlets

An electrical issue can indeed come right from the power source – wherever you’ve got your fish tank filter plugged into.

Check the functionality of your electrical outlets, power strips, extension cords, or any other electrical components you might plug your filter into. The issue could simply be with the power source instead of your filter. You may have to plug your filter into a different (working) electrical outlet or power strip to restore function. 

#3 – When to Consider Replacing Your Fish Tank Filter

Fish tank filters can run into some common functional issues. Thankfully, most of those issues have simple solutions. As you read a few times above, in some instances, you’ll need to replace your entire fish tank filter instead of trying to fix it. When exactly should you consider replacing your fish tank filter instead of trying to fix the one you have? 

The Motor is Non-Functional or Burnt-Out

If you’ve concluded that your fish tank filter’s motor is completely non-functional or just burnt-out, it’s time to replace your entire filter. Repairing and replacing only the motor of a fish tank filter can be complex, expensive, and time-consuming. Not to mention, repairing a motor isn’t always successful. In these instances, it’s better and more cost-effective to consider buying an entirely new unit. 

Your Filter Has the Wrong Flow Rate

A proper flow rate is necessary for fish in a tank – they need to be able to swim against the flow and not be blown around by it. Some fish tank filters have adjustable flow rate settings – but not all of them do. If your fish tank filter has a flow rate that’s too low or too high and can’t be adjusted, you’ll need to get an entirely new unit or add another unit to your filter setup. 

If the flow rate of your filter is too high and can’t be adjusted, you’ll need to replace your filter with one that’s lower-flow or adjustable. On the other hand, if the flow rate of your filter is too low, you can either get a new unit or add another unit to your existing filter. 

Broken or Missing Impellers With No Replacements

Impellers are a critical component of every fish tank filter – they suck in the water from the tank and push it through the filter. If you’ve determined that your filter has broken or missing impellers, and you don’t have any replacements (or a way to order replacements), you’ll want to consider getting an entirely new fish tank filter unit. 

Final Thoughts

Fish tank filters are essential for every fish tank setup. Like just about everything else out there, fish tank filters can have some functional issues. They may stop working completely. You don’t need to let a non-working fish tank filter send you into a panic or make you start planning a fish funeral, though – because now you know some of the main functionality issues in fish tank filters and how to troubleshoot and repair them. 

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