Jack I don't think it really matters whether you go with the aquarium or terrarium. The advantage of the terrarium is that they usually come with a well fitting screen top and an aquarium you'd have to buy or build a top. It seems garters to like to climb, so the extra height is good, especially if you're going to put the two adult girls in it. As for the light fixture being further from the floor of the tank you have a couple of options there. One, buy a higher wattage and thus hotter bulb. Two, give them an easily accessible basking spot higher up near the light. Then they can choose to be up where it's warmer or not. Here's a thread discussing enclosure size vs. number & size of snakes. http://www.thamnophis.com/forum/encl...ize-two-2.html Hope it helps