Tort frag suddenly beaching/receding

[justonwo]

I've had a tort frag for about 2.5 months. It's been in the same location the entire time and parameters have all been nice and stable. It started off brown and then turn a gorgeous deep purple. It began to encrust on the stand and some cool little green polyps started to emerge. Out of nowhere in the past two days, the base has started to bleach/recede. It looks like it's on its way out fast. What happened? Are there any emergency measures that can be taken to save it? This was one of my favorite acros. I'm really scratching my head since the tank has been very stable.

 

[NanaReefer]

Research STN or RTN. I'd be cutting away the dead to save the living.

 

[justonwo]

Yeah, there isn't much of a frag there to begin with. It looks like STN, though it's very hard to tell if it's not just bleaching. Definitely a bummer, as this frag had really turned a beautiful deep purple with great polyp extension. It only took a day or two for it to go south. I have noticed with NO3-PO4-x dosing when I start to get below 2 ppm NO3 that my acros aren't very happy. I would guess it's simply wiping out too much of the nutrient supply.