I know the main filtration is the rock and sand, and like you, I got it from an established tank so I haven't had a cycle really. I guess I can take the filter bag with the carbon out and just leave the sponge? I have a small mesh bag in the filter, too, into which I'm putting granular calcium to raise those levels (right now around 360). I noticed I have some little pods living on the mesh bag, that's good, right? I figure those would be in the sponge, too. I have all sorts of things crawling around the tank, my hermits are happy. Allthough, I added a few turbo snails and my hermits attacked one of them and are devouring him! Will this turn them into snail-eaters??
Thanks!