A colleague just started the fun with dealing with a big aquarium (his first). He asked for my advice, and I provided my best. However, being both engineers, we started discussing out-of-the-box ideas too. And one of them generated today this question - into my head.

I might be wrong, but sponges created especially for the mechanical filtering of aquariums tend to be expensive-ish - compared to other sponges.

So, are other sponges suitable for the task, for building a custom filter? I have in mind the sponges readily available for using in the kitchen or bathroom, or the foams used in mattresses.

Of course, I would experiment with them to find the ones which provide the maximum of benefits, but I wonder about the downsides.

2 Answers 2


Do not use kitchen sponges or other types of household sponges, they have been produced using different chemicals to make them softer and often fire resistant; this is toxic to life in water.

You can get filter sponges at a pond supply shop that are made for making filters yourself; most petshops have them too, but they do often cost more there than at a pond supply.

You do not need to change filter sponges unless they have lost their shape, it is often possible to clean the dirt out of them and use the sponges multiple times.

One positive thing with using the sponges again is you can keep some of the good bacteria alive in the sponges.

you can find several types of foam for filters by searching for blue filter foam on the net.


Coarse sponges are used on filter inlets as a strainer . Be sure to get "open cell" foam sponges. I have used them a few times in various filters as a final stage ( after fiber or other filter material) but for a small cell foam is is a nuisance to clean , so probably best to replace. Because I am replacing , I have found polyester fiber padding the best and don't mess with foam.I buy bed quilt size poly fiber at a sewing supply store and use a GOOD paper cutter to cut it into filter size . Each filter pad only costs pennies ( plus cutting time). Unfortunately,sissors do not cut it well .

  • hmm... you gave me homework... I will need to understand what "polyester fiber" is :) However, the idea seems great.
    – virolino
    Apr 6, 2020 at 6:04
  • One quilt pad makes hundreds of filters. Good ,sharp scissors will work. Apr 6, 2020 at 14:49

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.