1. how many volt light bulb do you need? does it differ from age of the GTP?
i assume you are asking if the GTP's need artificual light... the answer is no... they need no special lighting... do what works best for you... just dont let the snake burn himself... 
2. How do you know the size change in the PVC pipe as the gtp gets older? and how do you know WHEN to change it?
well if its too big it can cause problems... i try to make mone about the same size of the snake around...
3. How many times a day or week do you spray, and when you spray what do you spray? the whole enclusre or the snake itself? How long do you spray for? do you only spray when the humity isnt high enough or do you spray regardless what the huminity is? and what temp and humity is ideal for GTPS?
i spray about once a day... if the humudity gets low you can spray... but that should not be something you have to do alot... the humidity should stay fairly constant... the GTP will drink the beads of water off its back... for humidity i am usually between 60%-70%... and my temp is a constant 84 degrees... and at night it drops to 79-80...
4. When it is day, should the cage/tub see light? and when it is night should it be completely dark? as in turn off the Light bulb? how long do i need to keep the bulb on? and if i do turn it off, what if the temp dropps?
if you are heating with lights, you need to get night bulbs... or better yet... i have used 60 watt blacklight bulbs for large cages... but please make sure the snake cant get close... 60 watts will burn the hell out of a GTP... they are thin skined... i have never had it happen or heard of it happening... but i have burned my hand on one and it hurts...
5. How deep should the water be in the bowl?
i fill mine all the way to the top... most GTP's dont lay in their water dish... although it does happen... i have noticed a few of my new snakes did it when i got them in... but stopped and have not done since...
GOOD LUCK
Shiloh

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Shiloh Hawkesworth
kansas
(Midwest Serpents)