Yellow hammer not looking good

[jorge0912]

Had this yellow hammer for two years all the sudden is not looking good all I changed were adding new leds to my reef but it was doing good under them
It is the only coral in my tank that is not doing good everything else is opening

I do see some brown stuff peeling off the skeleton and then leaving it white is it releasing zoantheli?
I moved it to low flow and a bit of shade for now to see how it does
Any ideas of what it could be
Calcium 420
Alk 9.8
Nitrates 6
Anónia 0

 

[jorge0912]

Runing David Saxby program did take the par meter luz brand and saw all the par of the tank and where the coral were