Lighting issues, help!

My cousin who got me into this hobby not to long ago has had metal halides for a few months now. Since hes bought them hes had problems with his corals not opening and one actually completly died. Now im not sure the specifics on everything but if thats neccasery to find out the problem he's having ill ask him. So basically hes had his 6 or so corals since hes had my current tank and lighting (T5) and they were beautiful before he switched to metal halides. His water is right on other than calcium, which is 500 for some reason, but thats not too bad. His fish are all happy other than some snails which just recently died(we have no idea why that is either). and He just fixed his minor algea problems. So me and him have been thinking and its got to be the lighting. We just dont know whats wrong with it. So if anyone has had this problem let me know and ill be sure to call him up and find out all the details about his setup. Thank you!

 

Did he acclimate the light or just put it right on the tank?

 

What wattage, and how high off the water? What size of tank?

 

Hes got a 120g, 150 wattage lights, and thier 6 inches from the water. And yes he acclisimated the lights. But i think its cause he used to have the halides on 8 hours a day i just told him to lower them to 4 hours and see how that is. good idea or no?

 

I don't think it is your halides. I run a ton more light on a 150Gal.

 

Check the bulbs and glass cover for cracks. If either is cracked replace immediately and do not use. You are frying with UV.