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 fo 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.