Red nocturnal lamp

[jasonm96]

60W zoomed red bulb should do it, I definitely wouldn't go higher. You can get inaccurate temp readings with bulbs as they'll warm the air but not much of a moist substrate, which is why heat mats are used as additional heaters. Dry substrates are easier to take readings since the heat does not escape by moisture. Each time you mist the tank, the cooler water puts the temperature of the substrate down but not necessarily the air. I get the suction cup of thermometer and put it right to the probe sensor so when you place it down it's slightly raised above substrate, try that and see if it works. It might take hours to get a good reading