I'm very new to owning snakes, but at the advice of an experienced snake keeper at the pet store where I shop, I use a combination of Repti-bark and cypress mulch. I also put some moss on top of the substrate to help maintain humidity in the cage. I'm getting a pretty steady 50% humidity, and my snake had a successful shed today.

Bill
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It's not how many snakes you have. It's how happy and healthy you can keep them.