I've yet to have any problems with any of the substrates I've tried. I use repti-chips for my BP and adult king and have no issues so far. I use aspen for my juvenile corns and once saw a small piece in Otis's mouth so I pulled it out, but I'm sure I was just being over cautious, it didn't appear stuck and he probably would have spit it out on his own. Just to be safe now, I put a paper towel over the feeding area and they eat on that, so far has worked really well. Since you're feeding F/T rats, you made need a few paper towels.

Spot cleaning is quick and easy as well. Also, have never had any mold issues.