i personally dont have the bulb over the watersource cuz it heats the water up and it evaporates too quickly,i also dont keep my bullfrogs quite as wet/humid as alot of other people, im not saying their wrong its just what works for me,i have a 60w heat bulb at one end and the water source at the cooler end of the viv so my frog has a choice of hotter and drier or cooler and wetter,i rarely mist the viv probably only once a week i dont use heat mats and ive never had a frog estivate