Anthelia decline

[Enigma13]

I was wondering if anybody here might have some insight into my newest tank problem.

I had a huge patch of Anthelia that had almost totally encrusted an about 8" X 5" piece of live rock. It had been thriving and spreading for about 3 months. Then earlier this month it started to decline. At first a polyp or two would pinch off (literally looks like it is pinched off about 1 cm or so from base) and in the past week or two the decline has sped up. Now there is just a fring left on one side of the rock and a small patch on an adjacent rock.

The rest of the corals (Yellow leather, Xenia, Hammer coral, zoos, star polyps, rodactis and ricordia mushrooms) all seem to be doing well or thriving. There is at least 4-6" all around the anthelia, so I do not think it is overcrowded.

Water parameters seem good-- 0 NH3 and nitrite, about 10 nitrate, 390 calcium, 12 kH, pH 8.1-8.3, SG is 1.023-.025, and temp is 78-80. Lighting is 2X150W MH and 2X96W Actinic w/ 3 lunars. Tank is 144 gallon and anthelia is about middle of the tank.

Does anybody have any experience with such a die off, or any ideas what may be causing it. Thanks for any suggestions.

[blueboy]

mine seem to do a similar thing- the "pinching", but after a couple/few days they open up again. i assumed something was stinging them, but not all of the time. so they would withdrawl, but then come back out after the "coast was clear". is it near the leather?

[Enigma13]

They are not just pinching closed. They are being pinched off (like a nail clipper just snipped them off). They are staying open and waving and then just breaking off. They used to be close to the leather, but I have separated by at least a foot in case aleopathy was the cause of decline. I moved the leather, not the anthelia because I figured they did not need the stress of a move too. Hopefully, mine will come back too. Thanks for the input.