Funny I was going to post a nearly identical thread. I have the same setup, 20L w UTH and thermostat. I have to turn the thermostat to 100* in order for the glass inside the tank to get to 90*. The hot hide is 84 and cool hide 76ish.
Ambient temps are 73* cold side and 77 warm.
Is the ambient temp a problem and if so, is the solution a CHE or am I ok because of the hide temps?
Don’t mean to hijack but I think we have the same problem and simultaneously can benefit from any help..