Montipora Digitalis Problem

[Xanareef]

Just over two weeks ago my hubby brought home three small montipora digitalis frags as a gift for me for valentines. They are under 175w 10k MH in my 29 gallon tank. They are all an equal distance from the light, but two of the frags have been fading, while the third is doing beautifully.

By fading I mean they are greying up, from the chocolate brown with purple hints that they were when I received them. They are still extending their polyps, which are still rich chocolate brown, it's just the flesh that is graying.

Everything else in my tank is looking beautiful, my tubastrea, clam, acropora, pocillipora all look great and have polyp expansion during the day.

I'm having hubby test the water tonight when he gets home, as of last testing last week everything was right where you wanted it.

SG 1.026, 80 F, ammonia/nitrates/nitrites perfect, calcium was 380 and alk 2.4 meq/L, a little low, but not alarmingly. We're starting to dose kalkwasser tomorrow.

Any ideas on what is happening and on what to do would be helpful.

Thanks a lot,

Alexis

[reefrunner]

I have yet to get a purple digitata that kept it's color, there are often time when you cannot tell what might happen to your SPS's color when you change the lighting from what it was. Some will get more vibrant colors, some will stay the same and some will be drab.