Its important for ball pythons to have belly heat. It helps them digest thier food and it also heats them more efficiantly. As mentioned before the bulb will dryout the heat. You can use a regular light bulb in conjuction with an UTH it could be one of those fancy reptile ones or a human eat pad just make sure that you test them both out as far as setting go to see what temps they stay at. The ball python will know if its day or night from the light in the room. If you do use the regular light bulb be sure to turn it off at night or use a timer.

Also a 55Gal is a little too big for a baby. But it can be used if you provide lots of hiding places along with vines and areas of cover so they can pass from one hide to another without being exposed. When ball pythons are young they think everything is out to get them.