A little more clarification on Pit's answer:
Tanks typically have screen tops which allow heat and moisture to rise out of the enclosure thus causing heat/humidity to be lower than standard. Modifications can be made to keep heat/moisture from escaping but can take some time to get it right. There are ways of modifying a glass tank to become more effiicent with heat/humidity maintenance(there is a post somewhere which I don't feel like looking up right now).
PVC enclosures are more efficient at holding heat and humidity for your snakes needs. Some proof:
-When I used glass tanks, my humidity was roughly around 40-45% and I would need to spray the enclosure to get even semi-decent sheds from one of my BPs. Now humidity statys in the 60-65% range and he's had 2 perfect sheds since moving to his new enclosure. Some of my enclosures reached 80-99% humidity and I had to make adjustments to bring that down.
-Cool side temps were a little above room temp(around 72 degrees) in a glass tank, which is ok for some of my colubrids but needed another heating unit to raise ambient and cool side temps for my BP. With my PVC cages, I've had to lower my thermostat to get a nice 78-82 degree cool side with 88-92 degree warm side.
It's worth the money to lessen frustration and so far has reduced my electric bill as well. Though, I switched 7 snakes from glass to PVC at one time so I probably noticed more than some people.![]()