Keep in mind that the probe of the hydrofarm is not very accurate it can be (according to the specs) 2 degrees higher of where you set it or two degrees lower than where you set it. I am guessing that it has a one degree set point (? anybody know for sure?) where one the temp is one degree where it is set for it will set to off or on. So that means the unit can be as much as 3 degrees off of true high or low. I'd recommend that you keep that in mind when setting the unit, and try to set it where 3 high isn't a problem and 3 low isn't either. I'd say no higher than 91º (94-88ºF possible range)