As far as the bulb goes, it depends I guess on what you are doing with it. Growing plants? Do the frogs need some kind of UV light or something? Just lighting the tank so you can see? The most basic thing could just be a light for plants that fits in it the fixture. I think I've seen 18" fluorescent vegetative lights at Petco.
What kind of frogs are they? It looks good, but my general experience is that frogs typically need about 75% land and toads need about 50-50%. water/ land.