Hammer Coral Dying

Not sure what's wrong with my hammer coral. It has been in my tank for about 10 months and over the last month and 1/2 it has just been dying off. It used to be more than double this size then just slowly not opening up as much.
attached are some pictures.
No changes to lighting schedule, regular water changes. No changes in water or salt. No changes to tank inhabitants. All my other coral is doing well. I target feed all my corals with reef roids 2 times a week.

Tank is a 75g not drilled no sump, I run a aquaclear 70 hob, and a canister filter filled with live rock ruble rated for a 100 gallon tank, a eshopps 150 hob skimmer and (2) 540 power heads. Lighting is a Current Orbit 48-60" led light So it is the larger one leds go all the way across the 4ft tank. schedule is white sunrise for 30 min and blue sunrise for 30min 2 hrs after white comes on whites on 8hrs and blues the same. Sunsets the same.

tank levels are
salt - 1.024
ph - 7.9 or so I know its a little low but i have tried numerous ways to get it up and won't stay up
amonia - 0
nitrite - 0
nitrate - 0
phosphate - .10
calcium - 480
kh - 179

Attached Thumbnails