How to keep my aquarium filter clean?

Maintaining a healthy, thriving aquarium requires ensuring that you keep your aquarium filter clean. However, the varied types of aquarium filters, each requiring different care, can make this task appear more challenging than it actually is. Let’s delve deeper into the cleaning practices for each type of filter and explore the underlying reasons for each step. We’ll wrap up with some handy tips for optimal aquarium filter maintenance.

Cleaning a Sponge Aquarium Filter

Sponge filters are a popular choice due to their simplicity and effectiveness. They foster beneficial bacterial growth, which is crucial for the nitrogen cycle in your tank. Cleaning a sponge filter involves a simple but delicate process:

Remove the sponge from the tank:

Be careful not to disrupt your aquatic pets or plants in the process. Use a container to hold the sponge after removal.

Squeeze it out in tank water:

This is an important step. Beneficial bacteria reside on the sponge, and using chlorinated tap water can kill them. Always squeeze out the sponge in the water you remove during a water change.

Rinse until clear:

Repeat squeezing and rinsing until the water runs clear, signifying that the sponge is clean.
Reassemble and return to the tank: Once cleaned, return the sponge to its original position.

Cleaning HOB (Hang-on-Back) Aquarium Filters

HOB filters are great for small to medium-sized tanks. Cleaning this type of filter is a bit more complex, yet essential to keep the filter running efficiently:

Unplug and remove the filter from the tank:

Always ensure your safety first. Unplug the filter to avoid electrical accidents.

Separate the different parts:

This includes the motor, impeller, and filter media. Each part requires individual attention during cleaning.
Clean the filter housing and impeller: Warm water and a soft brush work well for this task. Avoid harsh cleaning agents that might damage the filter or harm your aquatic pets.

Replace the filter media:

Different types of media have different lifespans. Follow the manufacturer’s guidelines for replacement schedules.

Reassemble and reinstall the filter:

Ensure all parts are dry before reassembling. Once reassembled, reinstall the filter.

Cleaning Canister Aquarium Filters

Canister filters, due to their high filtration capacity, are perfect for larger tanks. The cleaning process is slightly more complex but ensures optimum filtration:

Turn off and disconnect the filter from power supply:

Safety first! Ensure the filter is unplugged before starting the cleaning process.
Drain the water and disassemble the filter components: Drain the filter over a bucket to avoid spills. Take care during disassembly to avoid damaging any parts.

Clean the filter housing and mechanical filter materials:

Warm water works best. The chemical and biological filter materials should be rinsed in a bucket of aquarium water to preserve beneficial bacteria.

Check and clean the impeller and its chamber:

The impeller is a crucial part of your filter. A dirty or damaged impeller can reduce filter efficiency.

Reassemble the filter, fill with aquarium water, and reinstall:

Ensure all parts are clean and intact. Once reassembled, fill with aquarium water to prevent air locks, then reinstall.

Cleaning a Sump Aquarium Filter

Sump filters are often found in larger, more complex aquarium setups. Cleaning a sump filter involves removing detritus from the filter sock or sponge and cleaning the protein skimmer collection cup. Always ensure to check and clean the return pump as this can become clogged with debris over time.

How to Clean an Undergravel Aquarium Filter

Undergravel filters are a somewhat old-fashioned but still effective form of filtration that work by pulling water and debris down through the gravel substrate where beneficial bacteria live. To clean this type of filter, you will need a gravel vacuum or siphon:

  1. Siphon off the debris: Use the gravel vacuum to siphon off debris accumulated in the gravel. Make sure to reach the difficult corners of the aquarium.
  2. Remove and clean the lift tubes: These tubes should be removed carefully and cleaned with warm water and a brush.
  3. Check the undergravel filter plate: If necessary, remove the entire plate for cleaning. This is a bigger job and usually only necessary if you’re seeing poor performance from the filter.
  4. Reassemble the filter: Once everything is clean, reassemble the filter and resume operation.


The cleaning steps for each filter type are crucial for several reasons. First, a clean filter works more efficiently, ensuring optimal water quality for your fish. Second, removing debris prevents blockages that could cause your filter to stop working. Lastly, it helps preserve the beneficial bacteria in your tank, essential for a healthy and stable environment.

Now that we’ve covered the cleaning process for different filters, let’s wrap up with some tips for maintaining your aquarium filters:

10 Tips for Aquarium Filter Maintenance

  1. Stick to a schedule: Regular cleaning prevents the buildup of debris and maintains filter efficiency. How often you need to clean your filter depends on its type and the bioload of your tank, but monthly is a good starting point.
  2. Never use soap or detergents: These can harm your fish. Always use warm water to clean filter components.
  3. Replace media as per the manufacturer’s guidelines: Overused filter media may not work effectively.
  4. Inspect the filter during cleaning: Look for any signs of damage or wear that could affect its operation.
  5. Use aquarium water to clean biological media: This helps preserve beneficial bacteria.
  6. Don’t clean all filter media at once: In multi-media systems, clean or replace one type of media at a time to avoid removing too many beneficial bacteria.
  7. Monitor water parameters: Regular testing of your aquarium water can tell you a lot about how well your filter is working.
  8. Understand your filter: Read the manufacturer’s instructions carefully. Every filter has unique features that may require specific maintenance practices.
  9. Be gentle: Many filter components are delicate. Handle with care to avoid damaging them.
  10. Maintain water level: For filters that hang on the back of the tank or have an intake tube, maintaining the proper water level is important for their operation.

~~~ Cleaning and maintaining your aquarium filter may seem like a chore, but it’s essential for a healthy aquarium. By following these guidelines and tips, you can ensure your filter is working efficiently and your fish are happy and healthy.

Image credit: Photo by Josephina Kolpachnikof

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