I have a mini-offset smoker, and the thermometer on the top has about a 3" stem. A thermometer placed on the grill surface reads about 25-30 degrees higher than the top thermometer. Should I adjust my temperature myloweslife.com to allow for this difference? When a temperature is specified (such as 250 degrees) where is this temperature to be measured? On the grill surface, or from the themometer located on the smoker lid?