I had the exact same problem with my snap lid tub. I got a CHE a foot above the middle of the tub, with a thermostat of course, and temps on all sides are perfect now. Hot side is 90-93, middle is around 80-86, and the coolest spot sits around 76-79. Now if you got a glass tank the CHE might drop the humidity so I highly suggest getting a tub or pvc plastic cage they trap the humidity inside. Also GET A THERMOSTAT not a dimmer. A dimmer on the lower settings can still build heat and overheat. The "Jump Start" digital thermostat is a great choice an only 30 bucks. Best of luck.