I really dont like apsen.Even though its said to be the best i really dont think so. when i first got my ball python which is also a tropical snake it wasent doin so good with humidity and it kept havin bad sheds. i would reccomend using Jungle Earth
Exo Terra - Products: Jungle Earth or if you wanna go with aspen make a humidity box with Forest Moss on the inside
Exo Terra - Products: Forest Moss. To make a humidity shelter all you have to do is get some sort of plastic container big enough for the snake to fit in and fill it with some moss. Be sure to spray the moss with luke warm water periodicly (about every 2 days) With these two things you should be able to make a nice looking naturilstic enclosure for you snake(the jungle earth would be the regular jungle floor and the forest moss could act as a burrow underground where humidity is high) I hope this helps you! I also forgot when making the humidity box make a little hole for it to go in and out as it pleases and make sure that the hole is smooth or it could cuts its self on a peice of the opening.