OP; You can never be sure you got it all without a total change. It's up to you to do what your comfortable with. Just a quick look through the forms will show you a varying level of how people keep their animals. And from there you can do what suits you best. I have NP cages, glass tanks and tried every substrate available. I'm a bit of a cleaness/hygiene freak. So in the end it's always paper towels. But I do like the look of substrates better. And my experience with Repti Bark, is that liquid waste travels much further out then you might realize.