Digi is dying

[R_C]

Hello everyone,
This has been happening for about 2-3 months now and I talked to my LFS and they told me it was something but for the life of me I can not remember what is it. All I know is that they told me to remove the pieces that were not being affected by this and watch them. Once I removed the rest of the frag it went on overdrive and is now almost gone.
Please help ID this and maybe prevent it in the future (that is if it can be prevented.)
Thanks in advance.

P.S. Sorry for the blurry pictures.

 

[cloak]

Is your alkalinity kept stable or is it constantly bouncing around? If it's the latter than this might be what's causing the coral to look like that. Nudibranchs is another possibility, although I'm not sure if a Montipora digitata is really on their menu so to say. How big is your tank? What kind of lighting do you have? Where is the coral placed in the tank?

http://www.advancedaquarist.com/2008/1/aafeature2

 

[luke33]

If it has been doing this for 2-3 mths its stn'ing which could be multiple reasons why. Personally if you have your parameters in check now I would cut the dead part off and hope it will recover.

What are your parameters? Phos, calc, alk, trates, mag, sg and what kind of light are you keeping it under? Whats your temp? Are you using RODI water?

 

[R_C]

Is your alkalinity kept stable or is it constantly bouncing around? If it's the latter than this might be what's causing the coral to look like that. Nudibranchs is another possibility, although I'm not sure if a Montipora digitata is really on their menu so to say. How big is your tank? What kind of lighting do you have? Where is the coral placed in the tank?

http://www.advancedaquarist.com/2008/1/aafeature2

My ALK has always been 9.8-10 until this last weekend that I started dosing calcium and alkalinity and now it is 10.2-10.5.
125 gallon tank
Placed a bit higher than the middle of my tank.
Running LEDs

What are your parameters? Phos, calc, alk, trates, mag, sg and what kind of light are you keeping it under? Whats your temp? Are you using RODI water?

Phos 0.25
Calc 415
Alk 10.5
Nitrates 0
Mag 1320
RODI 0 TDS
Temp 78

I don't see anything on it nor anything picking at it.

Also testing with brand new Red Sea Pro test kit

 

[cloak]

Like mentioned above I'm not sure if a Nudibranch would bother a digitata, but here's an article that's definitely worth checking out. GL

http://blog.captive-aquatics.com/captive_aquatics/2010/09/a-montipora-eating-nudibranch-primer.html

What other corals do you have in the tank? How long has the tank been set up for?

 

[R_C]

I transferred my 75G about 44 days ago, but that was set up for about 5.5 months.

BTW, Thanks for the link. I have read it and when i get home I'm going to inspect.