Someone here at the Millipede forum posted a message about what substrate to use. I have in front of me a package by Four Paws company "Naturebed" natural reptile bedding. Like the other person who posted, it's 100% coconut fiber. I mix this up with peat moss instead of green moss which has a different PH balance and what one should do is vary different substrates thru out ones tank. Put peat in one end of the tank and maybe some bark and coconut mixed up in another portion of the tank and maybe some decomposed leaf litter in other parts of the tank. This is the set up I used in my tanks in the past 12 months. I also been using 2 ultra sonic foggers which helps keeps things humid but not over do it. I have them on timers that keeps the residents in the tanks alive and healthy. robt szymanski