Hey Guys,

I have a 40 gallon breeder tank, 36 x 18 x 16 (LxWxH). It's in my finished basement in its own room about 10' x 5'. I don't have a snake yet as I'm setting up the tank first and want everything to be stable before getting one. I originally bought a large UTH for my tank, which was rated for a 50-60 gallon tank, its dimensions were 8" x 18". I coupled this with a lamp above as well, bought all different watt bulbs so I will have one that's just right and could change them out depending on the temperature outside or in my basement. was using 60-75 watt bulbs with the large UTH and temps on cool side of tank were around 85-87 and on the hot side around 94. I have the UTH hooked up to a thermostat. Thought it might have been too hot, so I got rid of the large UTH and got the Medium instead, rated for 30-40 gallons, which is 6" smaller (picture below) so it is 8" x 12". So far with a 75 watt bulb it is 79 on cool side and 87 on hot side (its morning right now) and will probably get to like 81 on cool side and 92 on hot side. Problem is winter is coming and will probably get cooler. So from what I described and with the picture below, do you think the Medium sized UTH is big enough for my tank? Or should I get the Large sized one back? The large one would come out to where the red line is marked on the picture. Haven't dealt with humidity yet since I haven't put the substrate in the tank yet, I'm waiting for my 3d rock background to come in the mail. Without anything in the tank, humidity with the large UTH was around 50-55, with the medium now its around 40-50, grated its also less humid in my basement now since it's been cooler outside. I'm just flip flopping and think I should have just stuck with the large UTH. Let me know what you guys think.