To OP: I have a wall hammer coral i have been struggling with for almost a year now. He is still alive, but im guessing by the grace of god. Mine looked like that when It wasnt getting enough light. Dont move it closer to the lights, extend the photo period. Especially if you have it in a nice, low/mid kinda mid getting some highs, but mostly low area. Not trying to sound confusing. But, finding where in my tank to place mine in flow was a nightmare.
I have mine on the sandbed of my STD 75 under a 4bulb VHO t5 running ATI Coral plus and Actinics. And if my splash guard gets salty and i don't clean it, my hammer lets me know. If my tank is over 80/80.5 again my hammer lets me know, skimmer needs cleaned, again he dont look right. He is my canary in a cage for my tank. Oh he also lets me know if my overflow filters and filter socks need cleaned.
For feeding. Ever since i started to target squirt Reef Chili twice a week on him and dose every other day Red Sea Parts A and B. He has been doing a lot better.
Im sorry if this is a bit long winded. I hope something of this helps. I would start by getting him in an area with little flow, just enough to make him wave around but not beat him up. Then increase your photo period by 1hr every 2 days. I now run mine from 10am until 11/12pm. I have 1 day a week where its "Cloudy" and i dont run my lights. My SPS are loving it and all my LPS are doing well enough lol.
You may think im crazy but my wife bought my hammer for me. Paid $300 for it loves it and i'll be damned if im gonna let it die.
Any questions about your hammer PM me i'll be happy to help. Im going to be out of town next few days so i might miss your update.
Good luck!
Forgot to add my paramaters. These do not fluctuate at all. I test religously.
Cal 420/440
MG 1340/1350
Alk 9.2/9.4
P04 who knows, i run GFO and have algae in some places. The green scale to be honest looks like 0, Hannah Checker reads 0. But i have come bubble algae here n there im not concerned with
Ammonia, Nitrate, Nitrite all 0