Hey EL, first I would make sure to elevate the tub onto a table or somewhere away from the floor. The ambient temperature can be managed with a Che on a dimmer, and will be more efficient if you situate the tub into a corner. You will have to tweak the ambient with your digital thermometer to determine your best readings. My quarantine tub is in a corner of the room and the Che is about 12 inches above keeping a ambient of 78f on cool end and 82f on the warm end. My hot spot is controlled by a Zoo med rheostat at 90f- 91f.