How are you planning to light it? I recommend figuring out a way to deal with top-off water if you're using bright light, like PC lighting. 1 gallon of water will evaporate quickly unless you cover it well, or have a way to drip water in.
By the way, a Hydor is a great way to stir up some turbulence in the tank, aiding in water flow, without putting in extra power heads, since you have little space to begin with
http://www.jlaquatics.com/phpstore/s...duct_ID=hy-wrd
Keep in mind, a tank that small probably won't hold a fish. It would be great for a few inverts though!
