The way my setup works, the fans go on and off with the lights. The fogger runs all day, and for 30min before and after the lights are on. It also comes back on at 12:00am and 3:30am, for 5min each time. During the day, humidity is at about 80-85% and that's with the fogger on it's lowest output...I have a Reptifogger, too ...the main point in having it come on at night is to cool the terrarium a bit more at night.