Heat pads are fine for some people, but your snake will still do better with a close-to-natural sunlight lamp during the day. They are sun-loving creatures and get depressed and don't want to eat sometimes without that light. Be sure to use a focused beam on one end of the tank so there can be a good temperature gradient. Choose an appropriate wattage so that the basking area gets around 85 while still not going above 75 on the cool side of the tank. 10 hours a day should be plenty. Let things go dark and cool down to room temperature (or a little cooler) at night.