acro dieing...help?

[Cesspool]

i was hoping someone here can help me with my dieing acro, ive had it for about 4 months (the acro) now and it was great about two days ago it started to bleach and lose flesh from the top of one of its branches and is slowly moving down. all my other stuff is fine including a monti digi and my hydro is is making great gains after the great febuary rockslide that almost killed it off. i also have a xenia that is slowly melting for no apparent reason but its been doing that for 3 weeks now ( it crawled up 2 inches from were i put it when i got it and started to melt. moved it 3 x still melting...)

tank param,

90 gal w/ 15 gal fuge (live sand, culpuras)

600 gph return pump
600 gph closed loop/ spraybar
200 gph powerhead for surface agitation

lighting
1 400w 10k halide on a 5 hrs a day
2 55w acitinic pcs on 12 hrs a day
2 55 10k pcs on 8 hrs a day

temp 80 +/- 2 degrees
amm- 0
trate- 0
trite - 0
ph - 8.3

did a 30% change last nite using red sea salt and ro/di water
other tank inhabs include
1 cleaner shrimp
2 gcbs
3 emerald crabs
snails and hermits
2 yellow tail damsels
ive had my this tank since b4 xmass the only thing different ive done in the last few days is scrape all the crud off my back glass (ive havent cleaned it since i set up the tank) and change my carbon
any ideas?
tnx

 

[lando]

Where is the acro located in your tank? Can you get a pic?

 

[MT79]

Ca and Alk numbers will help also. Do you dose anything?

 

[Cesspool]

i will get some ca and alk readings when i get a hold of a test kit, i dose trace elements 1x a week but i have always done that, i also feed phyto but i have been doing this regualry also i dose liquid calcium but this is also routine., my acro is in the middle of the tank directly under the halide about 3/5 the way up where it has always been since i alclimated to my tank then light months ago, in fact it has grown about at least an inch since i got the frag. ill try to get a pic but it dont look good now multiple branches are dieing ... the last time i did a ca/alk was about a week or 2 ago i think its was in the suggested range. i would understand if i did something major and my stuff started to die but i have been doing the same thing for the last few months and only now i have problems weird....

 

[steve-s]

Acro's are a fair amount more sensitive to their environment than the other corals you mention, including the digi's. Once an acro begins to RTN, it rarely reverses itself if ever. You would be wise to frag any healthy portions if you want to save this coral.

You will also need to determine the cause. From your posts you do not properly monitor the chemistry of the tank which can be "make or break" for this type of species. Please be sure you get your own kits so the alk/Ca can be monitored regularly. High numbers can often stress a coral to death.

Have you always used the Red Sea salt, what's your salinity and have you changed the bulbs/spectrum at all in the last while?

Cheers
Steve