As said before a 50 gallon long is just too big to keep proper temperatures and humidity. A heat lamp will suck any remaining humidity you have in that tank, which is not good. BP's need anywhere from 50-60% humidity.

I'd switch him/her to a tub or a 20 gallon long tank. If you would much prefer to have the 50 gallon, I'd suggest getting a different animal whose needs aren't as high as the BP. Remember, animal first - always.