finger leather needs help!

[Strider85]

hey guys, so my finger leather is freaking out for some reason...

http://www.flickr.com/photos/strider85/4347433539/
http://www.flickr.com/photos/strider85/4347427941/

Noticed two days ago that a few of the fingers were looking sketch... Now after a few days there is brown (I'm assuming) dead tissue. So my questions are:

1) what could be causing this? this coral is under quad t5s, decent indirect flow, no neighbors stinging it and no visible parasites.

2) can i frag off the bad stuff to save the mother coral? or perhaps use a certain dip? Will a recently cut leather coral let off any slime harmful to any of my other corals?

3) might it potentially get better if i leave it alone?

thanks in advance to any counsel you all can give... This coral is super nice when fully happy and open and really has a strong presence in the tank... Would love to save it!

Chris

[HOZER62]

Lets see some water parameters!!

[Strider85]

silly me...

sg 1.023, ammonia and nitrite zero, dKH 6 degrees, ph either 7.8 or 8.2, my eyes have a really hard time with the API test result cards, nitrates 12.5 ppm, calcium 500 ppm, temp varies from 78 in early morning to 80 at night.

Tank has been set up since early September, ~110 lbs of live rock in the main tank.

Other corals, all doing great, are zoas, toadstool leather, kenya tree, tubastrea, favia, huge anthelia, pagoda cup, birds nest, a trachyphyllia and an alveopora. Fish-wise I have a sixline, small yellow tang and coral beauty, 3 chromis, mandarin, and algae blenny. lots of hermit crabs and snails.

[gh0st]

Lokks to me like Low Alk/ High Calcium is causing a bit of an imbalance. With Alk around 6, your PH is probably on the lower side as well.

If you are dosing Calcium, stop for a while, and dose Carbonate Buffer more until CA drops and Alk is around 9 or 10 degrees KH. You're PH should then go up as well.

Give the leathers good flow and improve water, and they should recover.