I did have them in a 20 gallon (tall cause that is all I have other than 10 gallon tanks and the 40). They were starting to look a little cramped so I moved them to the 40. The burm is about 4 1/2 ft and the ball is almost 3 1/2 ft.
The temps are about 70-75 degrees F at one end and 80-85 degrees F at the other during the day (the temp changes through out the day because the appartment I live in is on the side of the building that the sun shines on, so around afternoon time when the sun hits the room more directly it warms up the room I keep them in even more). Night temps are 68 on one end and 72 on the other. They spend about 95% of their time on the warmer end because that is where I have the hide box at and they are usually hanging out in there.
No mucus is noticeable and the only yawning they do is after they eat. I haven't seen them breathing with their mouths open either.
With the temps I keep the cage at, do you think I still need to raise the temps any?