The 80w won't be powerful enough for a tank that size. I'd use at least the 100w. In my recent testing however, it seems that the output drops off quite a bit as it burns in. It can achieve basking temps at about 12'' above the basking area, but it doesn't put out a lot of UVB. I generally recommend using a T5 UVB tube in a fixture that has a reflector built into it for the best UVB. Then you can adjust the heat separately by changing the height or wattage of a halogen or incandescent bulb. If you do go with a PowerSun, I suggest getting the 100w and setting it at 10-12'' (check the surface temps to fine tune it) or going with the 160w and setting it higher at about 16-20''.