What Substrate Should I be Using with a Ball Python?

[ballpythonsrock2]

I've been using aspen for over 20 years. Never any mildew, and no respiratory issues with the snakes on them. The above statement is not true, ie it's not a guarantee. I've lived in the highest humidity areas and no issues with it.

I also like Aspen just fine. I got mine at Walmart in the pet dept. they were 4 dollars a small bundle. I always changed my substrate and dis-infected every 30 days. That worked good.