peeling hammer-head coral

[fresh]

Hi all,

I bought a large (6-7" when it is NOT extended) hammer-head coral from ocean aquatics a few months back and it was doing so good. It opened up nicely and stayed open as long as the lights were on.

2 days ago, I noticed that one of the sides/ends or whatever you want to call it has started peeling off! As if it wants to leave the coral. I have had this happen to me in a branching tourch or a small bubble coral, but not a hammer head. Will it leave the base as a whole? All 7" of it????

What should I do? Can I help it somehow?

The system is a 77 gal with 260 pc lights, 100lbs of lr, 4" dsp, and a precision marine HOT1+ skimmer. Readings are as follows:
temp 79
ph 8.2
ammonia 0.25
nitrite 0
nitrate 10

I have never been able to bring the ammonia or nitrate to 0, even though I do consistent water changes and have a small bio-load. I suspect my test kit is the culprit especially since my nitrite has always been at 0!!!

My bio-load is as follows:
1 naso tang
1 tomatoe clown
1 royal gramma
1 firefish
2 chromis
a few snails
around 10 corals (all doing fine except the hammer-head).

Please help. Any advice to help the poor hammer-head will be much appreciated.

Thanks

fresh.