Mercury Bulb suggestion... 75gal Tank HELP!

Hello! I'm relatively new to owning a beardie. I adopted a 9 year old dragon from a co-worker that has a lot of health issues (chronic constipation and poor diet habits). Shes is currently under vet care and we've finally gotten her on a good schedule and system to keep her healthy. Unfortunately the person who had her before me never exposed her to fruits and veggies so she never eats them. Our vet said with her mainly protein diet (plus daily lactalose) that having a mercury light plus a 2nd UV light would help her digest everything the best.

We moved her from a 30 gal that she came with. Which was way to small since she's almost 20 in tip to tail to a 75 gal. We're still slowly working on updating her tank. She intially came with a like 3 year old UV light which we went out and changed that night to a Zillo Desert light and about a month ago after our vet vist bought a exo terra solar glo. That died randomly this week after we turned it off for the night. So we have the zillo light in for now as a back up. But there is a clear difference in her behavior between the lights. Shes so much more active and happy with her mercury light . I'm just wondering if any one has any suggestions for one that might last longer than 1 month before I go buy another one of these. Any suggestions would help! Not sure I'm going to trust amazon reviews haha :lol:

She most likely acts happy and is active under the MVB as she's getting actual UVB. The the other bulb, however, produces barely any or possibly none at all.
I'd recommend this bulb and fixture for your main UVB, and then a 150-watt regular bright basking bulb for basking. However, if you feel the need to have a secondary UVB source you could go with a megaray MVB. However, do note this bulb may produce an odd coloration and also not get the basking temperatures where it needs to be which is 100-110.
The tube lights listed below normally last 6-12 months... but mostly 6 months.

https://www.amazon.com/Reptile-T5HO-Standard-Fixture-Reflector/dp/B01B209YQC/ref=sr_1_5?s=pet-supplies&ie=UTF8&qid=1523586973&sr=1-5&keywords=t5+ho+fixture
^ 34" T5 HO Fixture

https://www.amazon.com/Zoo-Med-26062-Reptisun-Fluorescent/dp/B00AQU8HKO/ref=pd_bxgy_199_img_2?_encoding=UTF8&pd_rd_i=B00AQU8HKO&pd_rd_r=ZNH52XHETCP3Y7K5FGA2&pd_rd_w=GIi1G&pd_rd_wg=oAEwd&psc=1&refRID=ZNH52XHETCP3Y7K5FGA2&dpID=31QDwNV8eSL&preST=_SY300_QL70_&dpSrc=detail
^ 34" T5 HO 10.0