Hammer coral isn't doing well. Help!

[daer119]

Hey everyone, long story short my hammer coral isn't doing well as you can see from the picture.
Now the extra information. This was one of the first corals I got about a year ago, my tank was freshly cycled, had a few clown fish in it, and with the blessing of my LFS, I bought this amazing hammer coral...... You don't need to tell me. If I knew back then what I know now I would NOT have purchased this coral. Despite my inexperience, ignorance, and new tank this coral has clung to life. And I am ashamed to say I did not realize what was happening to the trunk of my hammer until today. Hopefully, it is not too late and y'all can steer me in the right direction.
I have a 25 gal aio waterbox and my parameters are:
Nitrate 1
Phosphate 0
Calcium 460
Magnesium 1410
Kh 10

 

[Davileet]

The stems are just empty skeletons as the hammer/frogspawn grows upwards. The heads look happy enough. Just keep light flow and medium lighting. I would think that you should have a bit more growth for being over a year, but these things are one of the easier corals to keep.