Ok, so I have 2 digital thermometers, one on the cool side, one on the warm side. they are the ones that have the long cord and probe at the end that takes the temps. well i have them suctioned cupped to the SIDE of the aquarium, very close to the bottom, but its not touching the substrate, the cool side temp stays around 80, the warm side stays between 92-95. i have an under tank heater, and 2 heat lamps (my room is pretty chilly, stays about 70-75 degrees, so the 50 watt heat lamp (with a rheostat on it) keeps the cool side just right, at about 80. the warm side i have a heat matt, and a 75 watt bulb.what im wondering is do the temperature probes need to be TOUCHING the substrate, right on top of the heat matt?? because i had it like that for a while but the temps would be 93 degrees all the time with JUST the heat matt on, and the cool side would drop to about 70! i fixed this immediatly. but now im concerned that when i have the heat matt, AND heat light on, and the temp probe is not touching the substrate that its way too hot for her?? i am horrible at this heating thing, i cant get it through my head how its supposed to be!! its starting to stress me out. im constantly worrying about her. i dont know if this will help but my tank is a 20 gal r-zilla critter cage. please ask any questions you need to know in order to help me out. i want to give my little Maxwell (yes maxwell is a female lol) the best life possible.