I had a glass tank set on some wireweld shelves. The tank itself was on 1 inch blocks of wood, and the pad itself was plugged into a (zoomed?) reptistat (sp) We had the probe on the glass right over the pad itself, and the pad was set to low. It did very well for heating with the light on the hot end. I just caution, use a thermostat, because it does get VERY hot, and make sure to raise the tank to dissapate the heat. Also if you do plan on buying one, make sure it doesn't have auto-shut off. That sorta defeats the purpose.