We just got our bearded dragon 3 weeks ago and still confused with different information. We were told at the pet store to purchase the zilla UVB light and place it on one side of the 40gal tank, 12 hours a day and the heating lamp on the otherside 24 hours a day, 7 days a week. They first sold us one that's 250 watts and was too hot and replaced it with a 100 watt. What is the right watt and how long do you leave it on each day?