hammer coral

[ILIKECOUGARS]

I have hammer coral that will not fully expand, all other coral are doing fine, (frogspawns, candycanes, brain coral, torch coral). I pick up this coral about 2 years ago with 2 to 3 heads on it and now has 18.
Change the carbon in the reactor, did a water change with no results. It's been like this for about 4 weeks now. As I mention all other coral are doing fine.

Salinity 1.026
Cal 420
Alk 2.7
Ph 8.0
No3 25

Any idea what could be wrong with it.

[whatcaneyedo]

Is it being bothered by any fish? Or is it possible that it is receiving too much light/flow?

[ILIKECOUGARS]

I don't think it's receiving too much light or flow, as it's been in that location since I got it, and the fish don't seems to bothered it.

It's started to look like this, 6-8 weeks after starting n/p biopellets. Which is the only thing that I added to my tank setup.

Just wondering could it have something to do with the pellets? My nitrate has dropped from 50 to 25 ppm.