Definitely makes more sense in their tubs, think I just heard about seperate container at one point and stuck with it. No problems for 12 years. Now being in a wheelchair it really became hard to get them transferred. Got sick of it, no fun for either of us. Any tips how to limit the substrate from getting on the rat? Got three in tubs and one in a animal plastics cage. Any advice on how to make it smooth. It hasn't been fun lately with less mobility