How far away from the basking perch is the bulb? How are you measuring the temp? The reason I ask, is because that temp seems very low for a 100 watt bulb unless you are measuring it fairly far away from the bulb itself. Also, at that low temp your cham would most likely be spending a lot of time warming up, more than it seems like he is. His color sound OK, so maybe your temp readings are off. Simply measuring the temp incorrectly can mislead you. For example, if your bulb is 24" above the perch your cham sits on to bask, the AIR temp around the cham is usually cooler than the cham's skin surface. A regular glass tube thermometer can really only measure the temp of the air around itself or the temperature it's own glass rises to, neither of which is really telling you what you want. If you are using one of those stick on thermometers that is out of the direct path of the heat bulb again you may be seeing a temp reading that is too low. To measure your cham's skin surface accurately (which is kind of the point) the best way is to use a non-contact infrared temp gun. You point it at the cham and it will tell you the skin temp in just seconds. These temp guns are great, and they cost very little these days. You can measure the surface temp of literally anything at any time. There's no need for more than one thermometer for all your setups as you can simply move from spot to spot with it. ProExotics, LLLReptile, and some other frequent advertisers on this forum sell them for around $30. Rather than risk a burn from too much heat, see if you can get more accurate temp readings from the cham itself and then add light if you still need it. Does that make sense?