Exo-terra's blue night bulbs generate quite a good amount of heat, at least the 50 watters. They produce some light, but not a lot. The lights is also supposed to be non-disturbing, with its blue/purpleish colour. It's not optimal for viewing the frogs, since it's not that much light and the colour disorts the colour of the frogs, but it's a goos way to produce heat. Add a dimmer as well and you can fine-tune very well!