How are you measuring these temps? Additionally, what is your ambient temps in the terrarium on hot and cold sides?
Photos of the terrarium would be very helpful.
I'd recommend a dome with a 100w CHE (ceramic heat emitter). The CHE bulb will last longer than other bulbs especially if you have it on 24/7.
Do they really last longer? I've always used red bulbs and I've heard ceramics were more reliable but haven't given them a shot. Are they as effective at heat output as bulbs? I may pick one up and swap out my reds if they're effective and safe.