When I see the videos of large breeders they keep the adult females in small tibs on racks. how can a tub that small contain a cold and hot side? The ambient temperature must be prettymuch the same on both sides of such a small tub. No?
They have back or belly heat. They use a strip flexwatt heat tape kept at ~90 and the room is kept at a stable temperature to control the rest of the tub. Sure it radiates, but not so much that it's 90* throughout the whole tub. It might bump the cool end up a few degrees, so if the room is say 80* the cool end is probably about 82*. They need to thermo-regulate, and no one knows that better than the big breeders.
My tubs have a heat pad which is kept at 89-90* all the time, the cool side stays at 75 because that's the temp of the room and thats how they like it.
1.1 Classic Ball Pythons - Louise and Zeus
1.0 Poss. Granite - D*ck
1.0 Cane Corso - Benedetto
1.0 ACD/GSD Mix - Dino
1.0 Fat Cat - Jose