The moss thing is a good idea! I have large rocks on mine, but he still gets around it every once in a while. I use fine organic soil, so I'm not too worried about it. I'm not sure if you're asking to change out your soil because it smells? He maybe using one plant as a bathroom, or all! I know mine uses all of my plants equally, but I don't have any problems with smell yet. If it is the soil, I would just change it out to make it clean IMO I take all my plants out once a week and rinse them and water them good if they aren't getting it from the mist king, and I always find Loki's waste and clean it out, and that seems to take care of it