I have a tank that is 40l x 20d x 20H. My basking spot is 100-105 for my adult beardie (2 years old 22.5" long). My cool side now that it is winter here is 73-75. Mid tank is 80-83. Does this sound ok? My tank does have alot of ventilation (side vents and screen top) and I thought that would help keep humidity down but now I am wondering if it lets too much heat escape. Here is a pic to help.
It does sound like a lot of heat is escaping. What you could do is put a lower wattage household bulb on the cool side to try to get a temp between 78 to 82 with 80 being ideal. I would try a 40 watt bulb first. Let us know how you make out.
I had to use a 100 watt soft white bulb to get the cool side up to 77 right at the edge but most of the cool side is 80-83. hopefully he won't spend so much of his day in his hide. He has been eating and everything normally. Just hasn't been getting out from his hide and he should be basking after a meal.