I personally love eco earth(coconut grounds not chips). They sell in huge bricks in most gardening sections. it's enviromentally friendly, easy to store and helps keep the tank's humidity levels perfect, I use it dry for my desert animals, wet for my rainforest. If they eat it it won't hurt them and it doesn't mold. what more can you want I keep lots of my animals on it frogs,geckos,snakes,lizards. It' the best thing to use next to paper towels.