Sinularia dura necrotic

[Volacar]

Hi all,
New member and new nano tank owner here.
I have a 60L cube for 10 days now. It was already fully eatablished months before I bought it.
With zoas now opening up, only my sinularia are worrying me. One S.flexibilis opened once and is doing nothing For 7 days now.

Worse: Sinularia dura. These Spots of exposed skeleton (do sclerites form those needles?) might have been there or newly appeared but definitely grew while polyps didn't Show up at all.

Further Details:
25°C,
Salt 1025,
NO3 ~5-10
PO4 0.04
Kh, ph still waiting For Test
Water Changes after 5 and 7 days, ~5%
Protein skimmer now For 10 days continuously running
Two crabs, bubble Anemone and several softies. The tank was running for min. 6 months before I bought it.

Happy to provide more info, If it helps solving the problem

 

[Rocks reef]

Leathers in general can sulk for quite some time, especially after being moved. They look healthy to me, just "upset".
Those "spots" you are referring too are new growth were it will attach to the rock.

 

[Volacar]

Thanks!
So instead of more decay, This was damage from the move that's how healing?
Also Just today it started shedding...final prove that it's doing its Thing.

Edit: finally got the Missing Tests and need to (totally Not surprisingly) revise the Test-strip Results.

Ph 8.2
Kh 8
PO4 0.2
NO3 <0.5