Man, thats alot of substrate. I would get real sick of changing all of that and of buying all that bedding. Another thing is you should have two identical hides on each side. The reason they are burrowing is because they dont have a hide on that side, and their trying to cool/heat themselves on that side.

Is there a reason you use carefresh over say aspen, papertowles, contractors paper, newspaper or the industrial paper towels? I've never used carefresh but yes I have heard of it being dusty. Just keep checking on them consistently. Herps, especially snakes, will keep from showing symptoms until the infection or whatever illness is pretty far set it. It takes a real keen eye to spot anything before, and usually it really is impossible.