I want to make a simple sponge filter to toss into one of my tanks so that it is ready to go (that is, already colonized with nitrifying bacteria) when I need to isolate a fish. I have a commercial one, but it is so tall that there’s very little clearance when I put it in a 2.5 gallon, I’m not crazy about it, etc., etc. the basic design seems really simple, I just am not sure what to look for in a sponge. Can anybody tell me what to look for or give me a specific source? It seems like the kind of thing where you might be able to use something that was not marketed for it, but is perfect for the purpose.
EDIT: I guess one of my concerns, if using something not made for the aquarium is to be sure I’m not using something with toxins.
EDIT: I guess one of my concerns, if using something not made for the aquarium is to be sure I’m not using something with toxins.