Need help with a bleaching Acro

[natclanwy]

I recently purchased a large Staghorn acro and it looked okay for about the first week or so and then started bleaching on one branch on saturday and today almost half of it is bleached. I am trying to figure out what is going on since this is my first acro.
Here's a little history of my system, 55gal Tank is about 3 years old but I just rebuilt my 30 gallon sump and refugium last weekend and had it offline for 3 days waiting for silicone to cure and in the process my nitrates started climbing from less than 10ppm to about 40ppm. When I brought everything back online I was starting with a completely new sump system with new sand and new water (about 25 gallons). After I started it my tank clouded up and stayed that way for about 3 days before it cleared, I lost a candycane coral and my zoas and kenya trees stayed closed for about the first 4-5 days. Now everything but the Acro is looking healthy again, I am starting 5 gal daily water changes today to try and get my nitrates down after the water change today I am down to 20ppm.
Can all of this be attributed to the increase in nitrates or is there something I'm not seeing?
Current tank parameters
Nitrates: 20ppm
CA: 400
Pho: 0
DKH 11
Amonia: 0 not sure if my test kit is anygood since I haven't used in a long time
No Nitrite test

 

[yosemite sam]

Is the tissue coming off of the coral? It sounds like the coral has RTN (rapid tissue necrosis), which is different from bleaching. In most cases of RTN, there isn't much you can due besides clipping some of the healthy branches as frags and hope they make it.
When did you add the coral relative to your work on the sump? Most acropora species can be very sensitive to water changes, especially if they are new additions.

 

[natclanwy]

I was about 4 days before I started on the sump, didn't think about my plan to redo the sump the next weekend before I bought it

Looking back I would have waited just didn't put the two together at the time.
Not sure whether the tissue is coming off or if it just bleaching since I have never dealt with a diseased or dying coral before now, I have always had good luck. But the white area started at the end of a branch and is progressing down the branch and up to the rest of the coral.

 

[coraljunky]

What's your turn over(flow) and lighting?? How did you acclimate??

 

[natclanwy]

Turnover rate before the Sump overhaul was about 1300gph now it is about 1600gph
I have 2 250w MH and 4 55w PC about 8" above my tank
Coral was drip Acclimated for about 3 hrs not sure if was a very complete acclimation since the LFS sent the coral in a 5 gallon bucket with about 3 gallons of water in it since this piece was so large.

 

[str8salt]

Do you have a picture? If it is that purple stag and it is turning bright white,like looking at the skeleton,the flesh is falling off. Look to see if you can see polyps on the "bleached" area. If theres still polyps then probably bleaching, if not then tissue loss. If it is tissue loss I would suggest looking gor a viable piece for fragging. Holler if you have any questions about fragging acros. Hope it works out,.....

 

[nycbob]

did u light acclimate it? i think with all the change u did recently, its probably very stressed.

 

[natclanwy]

It was the purple stag

and it has totally lost its flesh, I tried fragging off a couple pieces but they lost there flesh also so I am way bummed out. Hopefully this had to do with my sump rebuild and my next try will be successful and hopefully with a cheaper acro. Things are starting to level out in my tank haven't checked Nitrates in since Thursday and but they were down to 15ppm then so I will do another water change today and recheck everything and see where I am at.