light / heat confusion ?!?

[DonLisk]

Heating the enclosure is going to mainly depend on your rooms temperatures. A whites should have enclosure temps arounf 78 degrees in the daytime and 68 to 70 degrees at night. If your room is normally 70 degrees then you only need a compact florescent bulb to add a few degrees and create a day and night time cycle. You wouldn't need a night light at all.

Since your frog is going to want a ton of height your going to find the frog will climb to the top and try to push it off and hang from it. The screen on top of the Zoo Med is going to get very hot with a 40 watt bulb right on it and your going to lose a lot of humidity out the top is you don't close a little bit of it up with a piece of glass or plexi.
I've never used UTH with any of my frogs except in the winter when I want to create a warmer side of the tank. I place the TH on the side for this.

I myself like the matching hoods they do for the Zoo med and Exo enclosures and would think more on a compact florescent. A 15watt CFL bulb with 6500K color temps is perfect for your size tank and a 24 watt for a 18x18x18 with plants and I find them at Walmart under the Reveal Label listed as Daylight 6500K. Here is a link to the case price but you can get in two packs in stores. Walmart.com: GE Energy Smart Spiral CFL Daylight Bulb, 15W, 12 Bulbs: Decor

UTH heaters work ok but can dry out substrate quickly, and the heat has to make its way through the drainage layer and then through the substrate to change the ambient air temp it the tank. Not the best thing.

If your room is always cold, then add a night 15 watt bulb in red or moon to keep temps up some. I think the 40 for night is going to be too much. Keep in mind that the forg is going to get to that metal screen on top and you don't want it scalding hot.