ive tried paper, coco chunks and aspen. ive found that aspen is my favourite out of all of them but no matter what substrate i use i find that they move the substrate and they poo directly on the tub or it will get stuck on the side of the tub and its getting really annoying having to clean every single tub and well thats why ive gone off of using paper. Is there anything i can do to keep them from not pooing on the tubs or moving the substrate just to poo on the tub?