What I did when I got the dimmer was I lowered it to about halfway, I took temps about 20 minutes after that and adjusted until it was around 88-92. Then during the day sometimes it gets to like 93....so I'll just lower it a teeny bit and retest a bit later. It's quite sensitive, so once you get the general reading you want you'll only be adjusting it a tiny bit, like 1/2 mm each way is all. Takes some getting used to, but once you get the general hang of it, it becomes second habit.