To much light?

[Saltfun2003]

After my sps 120g crashed i downsized to a 65gallon. It has been up and running for about a year with a few shrooms and a few LPS. I have recently gotten back into sps. The problem i am haveing is some stags are dieing from the tips down and encrusting from the growth edge in. Not all coral is affected just some of them.

water chem
cal 430
ph 8.1
kh/alk 7.7/2.74
nitrite 0
nitrate 25 (little high)
mag 1440
phosphate 0

nitrate a little high think its because i added about 15 pounds of base rock.

Wondering if its maybe just to much light (if this is possible) Lighting is 2 250 hqi 14k phoenix bulbs

other equipment mrc 2 skimmer
tunze 6000 and 6060
mag 10 return
have been haveing a 3.5 deg temp swing waiting for new heater.
thanks in advance for any comments

[Saltfun2003]

this is pic i shot real quick before the lights go off. the polyps are still there kinda recessed. most base is gone
http://reefcentral.com/gallery/showphoto.php?photo=280053&papass=&sort=1&thecat=500

[dwilly]

It is possible to have too much light, but I'm not sure that is your issue. What is your current photoperiod, you might be able to run those mh's for a shorter time?

[Saltfun2003]

halides run for 11 hours a day since i run no other lights on the tank

[dwilly]

IMO 11 hours is a lot for 500 watts over a 65 gl tank. You could start reducing that by about 30 min every week until you start seeing better results. I have T5's and only run all 6 bulbs for 7 hrs/day. I've heard people running as low as 4 hrs/day for their mh's. You might also want to consider getting some T5 or VHO actinics (or similar) to run for an hour or so before and after the mh's.

[stony_corals]

It's not an issue with too much light... heck, back in the day I had 2 x 400 iwasaki 6500k over a 58 oceanic..... how stable is your alk? Could be one of those things that make sps so challenging, mysterious die off.

[fijiblue]

Agreed - I run 2 250 DE's over a 30 gal with no ill effects...