Hmm, I have 10 gallon long terrariums for use with hornded frogs, which are a few inches less in height compared to a 10 gallon regular. I have three thermomenters in there, one at the top which reads 36C, one in the middle which reads 32C, and one at the bottom which reads 29.5C. This is with 2 15 Watt bulbs. I use 60 Watt reptile bulbs for lizards, if I were to use them on my horned frog enclosures, it would be way too hot.