Help with struggling Pavona maldivensis

[evolust]

I have a large Pavona maldivensis that is slowly dying. It turns white then brown from the edges toward the center of the colony. I have it about 16" deep under dual 400W MH 20K In medium to low flow.
Temp steady at 80.0
CA 400
ALK 3.25
Nitrate 0ish
Mag 1400

All other sps are doing well. I assume its a light/ flow issue. Where should I try it? TIA

Here are a few pictures from a few weeks ago

[happysak]

try to put Pavona in shady spot. They don't like a lot of light. I keep mine on the bottom 24" deep under 250 MH

[JetCat USA]

Mine is only a small 4" one but it's growing nicely in pretty high flow from a Tunze Stream 6100 aimed directly at it about 16" away, you might want to pick up the flow a bit and see. mine was just over 3" when i got it with a good 3/8" of white around the perimeter from recession which has all recovered. I've got it high in the tank under overdriven T5s so the polyps don't expand out as much as yours with lights on, but do at night.


edit: wrong pic... oops

[happysak]

Oooh, it is a picture time

[tmz]

I kept mine about l6inches down under 250w14ks. After about a month it did what yours is doing. I moved it to a pc tank and it healed up aftera couple of months.