How To Clean Aquarium Filter Sponge – A Quick 3-Step Guide

Sponges have been used in aquarium filters extensively, either in sponge filters or in three-stage filtration since the beginning of the modern filtration system. 

Sponge functions in two ways, mechanically it traps debris, dirt, and large particles and provides surface area for the bacteria to colonize. 

Therefore, the aquarium filter sponge is a vital part of the filtration process in your tank. Unfortunately, sponges are more like garbage cans, and over time, the sponge gets clogged when it’s full of fish trash and detritus. 

It’s important to clean that thing out and reset it so that you can maintain healthy water conditions for your fish.

This blog post is all about how to clean your filter sponge, which everyone needs to know how to do if they have an aquarium. However, if you don’t know how or are too lazy, this article will tell you what you need to do – it’s super easy!

How To Clean Aquarium Filter Sponge

An aquarium filter sponge has colonies of beneficial bacteria. These convert ammonia into less harmful substances for your fish and other aquatic life to keep them healthy and comfortable.

Cleaning the sponge is a straightforward task, but there are ways you can get it wrong. Incorrect cleaning of the aquarium filter sponge may end up losing good bacteria.  

Suppose the sponge is the only filter media of your aquarium filter. In that case, it may lead to a biological crash, and you may observe new tank syndrome in your tank. So, a proper cleaning method needs to be followed to avoid such unwanted scenarios.

Step-1: Resist The Temptation To Clean In Tap Water

Do not use tap water to clean aquarium sponge

It’s tempting to clean the sponge with running tap water. But never ever do that because it contains chlorine and chloramine to kill germs and bacteria. Suppose you wash the sponge in tap water.

In that case, it will be sterilized, and you will lose the bacteria making it capable of converting ammonia. However, you can use tap water but make sure to dechlorinate it first. 

Step-2: Perform A Water Change And Use Old Tank Water

Use Old Tank Water to clean aquarium sponge

The best way is to use the old tank water and for that perform a water change (10-15 %) first. Save some of the water and put that into a bucket. Submerge the sponge in the water and gently squeeze and release it so that all that brown gunk goes into the old tank water. 

Get some more old tank water and keep wringing it out until that water is not that brown anymore. You might need to repeat the process two or three times. One caution note is never to let the sponge dry out during the cleaning process. 

Step-3: Reuse Some Old Tank Water (Only If Necessary)

Reuse old water after cleaning aquarium sponge

After cleaning, the old tank water in the bucket contains some bacteria that sponges were carrying. Therefore, if you have only one sponge in your filter unit, you should use some water from the bucket again in the aquarium. Following this way, a portion of good bacteria will be reinjected into the tank. 

Suppose you have multiple sponge filters in use or a three-stage filter with separate bio-media for bacteria colonies.

In that case, the reuse of the old tank water again is not required. Because there are other sponges or media to keep the nitrogen cycle running. However, ensure that all the media are not cleaned at a time. 

How Often Should You Clean The Filter Sponge?

Generally, you should clean the filter sponge every 2-3 weeks. But actually depends on a few factors; types of filter you’ve been using, aquarium bioloads, water parameters, etc. However, a specific routine maintenance schedule will be much more helpful. 

If you are using a sponge filter, there are a few signs you can look for. First of all, if you listen to the bubbling sound and it’s a lot quieter than usual.

Or, visually, you’re looking at the bubbles. It’s just not as many are floating up; that’s a sign that your sponge filter is clogged. Also, if you observe fish waste and other particulate matter in the aquarium water, that’s another sign. 

The cleaning frequency of the sponges used in HOB (hang-on-back) filters or canister filters is less. Cleaning once a month is good enough to keep everything nice and clean. 

Can You Reuse The Sponge?

Absolutely, you can reuse the sponge, and I’d suggest it. Sponges carry some good bacteria on them. However, over time sponges start to fall apart. After squeezing, it’s OK to reuse as long as it comes back to its original shape. But if it doesn’t, it’s time for a new sponge. 

The replacement of the sponge is a bit tricky. Removing the old sponge and putting the new sponge without cycling may hamper the biological balance.

Because when you remove the old sponge, you are taking away the bacteria it is housing. So, replacing the sponge should be done carefully. I have a detailed article on how to change filter cartridges in the right way; you can read that. 


We hope this article has been informative and that you’ve learned a little bit more about how to keep your filter sponge in good condition. 

If you have any questions or comments regarding how to clean aquarium filter sponges, please leave them below!

Sujit Modak

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