Well, it's usually easier to use a screen cage. Ventilation is the main problem. it's entirely possible to use a glass tank for a chameleon - especially a big tank - but it makes keeping the animal much more difficult.
Veileds don't need humidity as high as other species, but they prefer a higher humidity than most people believe. Though they come from a desert country, they live mainly in the oases. They can tolerate long periods of dry weather with no rain, but they do better if they have water more often.
Glass will sometimes confuse the chameleon, and they'll endlessly try to climb through the glass.
Chameleons have complex lungs, and if the air is stagnant, then respiratory infections are likley.
Air flow can be fixed with a small fan - it's the glass that's the main problem, especially with veileds. If they can reach the glass, they might try to get through it. With screen, they know there's a barrier.
In my opinion, glass is best used only in large cages where the animal will not be able to reach it. A display case, or a zoo-like exhibit.
45 inches by 45 inches by 60 inches high would be huge, and in my opinion, perfectly suitable for a chameleon if ventilation is maintained. If it's 60 inches long (ok it's a tank, so I assume it's not 60" high!), then it would be fine if it was mounted off the ground considerably.
Don't use a waterfall. Especially in a tank. They get dirty really fast, and are a pain to clean. With the lack of ventilation in a glass tank, they'd just increase the likelihood of bacterial problems.
and it's really hard to emphasize the difficulty in cleaning a waterfall, and how poor a choice they are with chameleons - they SEEM like a perfect device for them, but they are not!
Water is another reason why tanks are often more problems than they are worth: chameleons drink from water sprayed on leaves and dripped onto the plants (like rain). It often takes a lot of water dripping to get them to drink a small amount. you have to contain the runoff an dremove it. A REAL pain - I know, been there, done that, many times, different ways - it's always a pain.
Unless you want to drill a hole in a 45'x45'x60' tank. And if you have a 500 gallon tank, and you're planning on drilling a hole in it... hell, if you're planning on using it for a lizard.... I'll make you a deal: You give me the 500 gallon tank, and I'll supply you with the equivilant size screen cage AND a beautiful male veiled chameleon!
