We are fairly new to keeping a ball python. We have one BP in a 65 gal tank. At present we have a heat lamp, blue lamp, and red lamp. All are 60 watt bulbs, but we can't seem to keep the temp in the tank above 80. What sized bulbs should we be using. Our snake seems to be happy and is eating like a pig, but almost always seems to be cold, with temps in the tank between 77 - 81. Please help.