I am just starting to setup my bullfrogs new home, and put a glass partition in it. On the water side, I will have gravel, and on the other I was thinking gravel and then something on top, but my mother insists it be something non-messy, like gravel but I don't want my frogs ingesting it nor crickets cramming themselves between huge pieces of rock. Unless coconut coir is less messier than I think it is, is there any safe substrate that when the time comes to dismantle the tank it doesn't leave a muddy mess? Thanks.