Those absolutely need thermostats... I have yet to come across one that did not.

Here are 2 good ones, the ones sold in pet stores are junk (overpriced too)

Budget: http://www.amazon.com/Hydrofarm-MTPR.../dp/B000NZZG3S

Quality: http://spyderrobotics.com/

with 2.5-3 inches of substrate the heating pad isn't going to be able to get the right temperatures. they only heat the bottom of the cage and not the air in the cage so you will need a thin layer of substrate, 1/2" thick or less. Also simply having a thick substrate layer does;'t make it any sdafer. BP's can and aty times will dig down into their substrate and lay on the bottom of the tank (which with an unregulated heating pad can easily be hotter than 120 degrees.

Make sure that you put the probe of the act-rite on the floor of the cage directly over the heating pad