Yea they do not like high temps. What I have done is take my UTC heat and move it to behind the back of the tub. This seems to keep them happy. I don't really worry to much about temps and measure much. I just adjust and judge the snake. When I had my heat under the tub with my Black Milk he never went to the hot side. Now with it in the back of one side of the tub he goes there after a feed and spends most other time at the cool side. Cool side is about 74. Hot side was 83 last time I bothered to check. Same as I keep my Spotted Pythons by the way they don't seem to like it as warm as a boa or corn, etc either.