Repti bark is said to be fine for ball python and I believe for your boa as well. I've never used it though, so I can't offer personal experience, the only thing I would worry about is a tooth getting stuck on a piece of bark. I'm sure someone who uses it will chime in. Personally I use about a 50/50 mix of aspen and eco earth. Bottom inch all aspen, top inch to 1.5 Of eco earth. Loki tends to mix it up as he slither through it and beds down.