I use Cypress Mulch for my Ball pythons' substrate. It holds in humidity very well and it's totally safe. It does not carry external parasites (mites, ticks, fleas, etc.) which some people may say it does but I've been using it for a while and I haven't had any problem with it. Since you have a glass enclosure, I'm guessing it has a screen lid. If you purchase saran (sp?) wrap that holds the humidity in very well. It's a plastic sheet that you put over some of the top of the enclosure, probably half or less, and it holds in the humidity very well. Also, to raise the humidity level, mist the enclosure and substrate with warm water. The humidity level should be between 65%-75% when a Ball python is shedding. When it is not shedding, humidity levels should be between 50%-60%.