I don't usually use the chips for tortoises. Seems like too much incidental ingestion for my liking. The best substrate will be fine grade orchid bark. It inhibits mold and mildew, and if you use a thick enough layer, you can keep it damp on bottom for humidity but still dry on top which is what is needed for a RF plastron to prevent shell rot.I use coconut husk chips. With the plants, this combination seems to be working for me to keep up the humidity. Do you think this is a good substate to use with a redfoot?