Since December when I purchased my leo, I was running the UTH on a dimmer, which was fine for winter temps in my home ect. Fluctuations did occur but they were minimal and the range never exceeded 94 degrees. That was until this past month when the outside temps rise, ambient temp of my home rises and the UTH just keeps running! Temps were rising to close to 100 degrees F. So, with some great advice from this forum I purchased the Hydrofarm MTPRCTC for like 30 bucks on Amazon. What a game changer! This thing is so easy to use, set it at 91 degrees, it rises max to like 94 then shuts off and drops to 88 then kicks back on again and so on. I've even found that my leo is spending the proper amount of time in his warm hide now which as you know is critical for digestion. So, my point of this post is that for those of you still on the fence with purchasing a thermostat, don't hesitate. If your running a dimmer, use it for your overhead lighting and not for your UTH. Thanks to this forum with some of the best advice I've gotten to date!