I had plans on 2 bulbs in mine so i off set the first bulb and got my thermostat in an angle about 2-3 inches away from 60w bulb. I've seen temp go to 102 and low as 96. It has been holding steady at 99 with no fan so I think I'm not going to add the fan. My next one I make will be bigger, since i ordered a 4 pack of 120mm fans from Amazon. I now have another thermostat because my water heater gave out so i scavenge it.