whats happening with this alveopora

[reefo420]

What's happening to this alveopora?
it was doing good for a month and half untill two days ago
water quality has gone better
when it was introduced:
Nitrate: 32ppm
phos: 2.1ppm

Now:
nitrate: 17ppm
phos: 0.3

Any idea on what could cause this, it hasn't been moved or anything else

 

[tbrown]

It's just hiding. Mine does that when Hermit crabs mess with it or when the flow changes. Sometimes they can hide for a couple of days and then come back out.