Im sorry this is off topic but after reading your last post I cannot let it go without saying anything. You state very clearly that it is your first reptile so I am going to guess that it will be your sisters first reptile. If that is true I cant help but stress that she does NOT get a water dragon or a tree monitor. Especially the tree monitor, they are not a beginners reptile and neither of those animals belong in a 10 gallon aquarium. I also stress that you make sure your sister does her homework before she gets anything, it sounds like this will be a spontaneous purchase of whatever she seems to like at the expo. Bad idea unless you are well versed in the care of the animal you pickup. While you have the animal in your care is not the time to learn how to care for it. Not trying to berate you or your sister, I am just looking out for the animals well being.

Now a little more on topic, just because you take your boa out of her cage for an hour or more daily does not mean you can get away with not having a proper enclosure. This 'exercise time' is not a substitue.