The coil does not spread the UVB out like a regular florescent. The UVB is only in one little spot and if your cham is not in that spot then they are not getting and UVB, but with a regular florescent the UVB spot is much larger and the cham can get more UVB. The Regular florescent luminaire usually have much better reflectors with means that less of the UVB output is being wasted going up.