WHAT is Happening to my Duncan Colony

[threebuoys]

I've had a thriving Duncan colony for 6 months that over the past 3 days has experienced a catastrophic death. Everything else in the tank, as well as several other Duncan colonies are fine (at least for the moment). In fact, a stalk from a different healthy Duncan colony can be seen along the left edge of the photo. You can see that several heads bleached out over a couple of days and the remaining heads over the course of today have covered over with a gel. I'm trying to get a video that shows the gel waving in the current.

Does anyone know what this is and how I should deal with it? Nothing new in the tank in over a month.

 

[jabberwock]

How old is the tank? How many gallons, what are the parameters? A full tank shot can be helpful.

 

[threebuoys]

125 gallons
3 years
Corals 2 years
Plating Montipora, hammers, chalices, blastos, acans duncans at different locations,etc are all growing and thriving. Only parameter that's a little low is calcium at 380. Had a dosing problem and its edging back up. Phosphate at .12 is a little high based on Randy's recent guidelines. I also had an acro frag that was 3 months old bleach overnight 2 days ago.

 

[jabberwock]

Is it possibly coral warfare?

 

[threebuoys]

That is possible but I have never experienced it and don't know what to expect.

 

[His Coral Highness]

Brown jelly disease?

 

[Colton Yuchnewicz]

looks like something is surrounding its exo skeleton?