Mercury Vapor Bulb & New Tankmate

I finally just introduced a captive bred male terrapin (3 yrs old, dark phase northern & really small, just about 4″ and a tiny head) to my existing 1 yr old female who is bulky and already pushing over 4″. Their reaction to each other was fascinating! They kept nudging each other, pushing each other away, following each other around the tank, etc. The odd thing was that neither seemed to win dominance as both would alternate this behavior until the other would submit then would go about their business. The male had been with other turtles prior to coming to me so he seemed unphased for the most part. The female seemed very interested in this new intruder and almost seemed to “sniff” the hind legs of the male. I still have to watch them carefully since my female hadn’t been with another terrapin since she was a hatchling and her then tankmate died. They seem fine which is a big relief. I’m guessing the rotation of testing for dominance will subside after they grow accustomed to one another? With the occasion of setting up a larger tank and introducing a new terrapin, I figured I would finally try out one of the 100 watt mercury vapor bulbs that everyone loves so much. They are expensive so I was apprehensive at first but I want my turtles to be as healthy as possible. I went to screw in the bulb (carefully) and the glass broke from the metal threads. I am going back to the pet store tonight to get another one, hopefully under warranty. I am still nervous about these bulbs. They say that any water splashing onto them could cause them to break. Shaking could cause them to break (cashier throwing it into a shopping bag?), among other things. I have a lamp stand that extends high above the tank and allows the lamp (rated up to 250watt) face straight down as the directions also suggest. My concern is that this is an aquarium full of water and has two aquaclear 300 (75 gallon) filters running all the time in a 75 gal. tank with water droplets splashing out of the water from time to time. I also don’t want the bulb too close because they get so hot but I can’t go any higher. The directions said a minimum distance of 12″ was necessary and I had over that but it kept mentioning directions for a terrarium, not aquarium with a high water level. If I lower my water then the terps have less swimming room and the filters will have to drop the water further. The cork bark basking area is at the highest water level I could have without risking the turtles escaping the tank and it feels like a good place. I want to try this out but it seems like its not going to work with my setup (I can’t hang the light from the ceiling). Does anyone have any suggestions that have worked for you? -Scott McDaniel