Hammer coral problem

[rossco838]

I have this hammer coral and for the last week it has not extended fully, today it looks like this. I just started keeping corals so I'm unsure what to do. All other corals are fine, sps included. Parameters are
n03-0-2ppm
P04-.03
Mag-1350
Alk-11dkh
Calcium-440

 

[rossco838]

Updated pic in a matter of 5 hours