What wrong with my Green Nepthea?

[JGTPA]

My tank is 3 years old and has predominantly soft corals. My nepthea has always been one of my healthiest looking corals. However, a few months ago I noticed a light brown ring just above it's base. Other than this ring, the coral looked fine. Over the past 5 days it began leaning and is now almost completely bent over. I tried moving it to a new location/flow in the tank, but that didn't help. Any idea on what's going on and what I can do to fix it? All other corals and fish are healthy.
pH - 8.2
Nitrate - 20
Phosphorous - 32
Calcium - 380
Salinity - 35

 

[Reefing Madness]