Duncan not opening

So I got a Duncan a more than a week ago, and still not opening, I have moved it once to a different location to see it he will open and he is still closed. This is my second time trying a Duncan, my 1st one opened fully the next morning but after 2 weeks he started dying, I think from a lack of calcium. Now my calcium is good.It does not look like he is dying but just not opening. All my other corals are doing just grate.
75G tank with 6 ATI T5 bulbs.

Where do you have him as far as light and flow?

right now bottom middle of the tank close to the front

That doesn't actually answer the question...

well flow he is getting medium to high

And lighting? They usually like lower moderate flow.

Duncan still not opening 3 weeks already, I have moves him 3 times. everything else in my tank is going good, one thing I do know is that phosphate probably is on the high side, I need to change my carbon and GFO which I’ll do this weekend, but is that the problem???

how long have you had them . i found they do better in a less lighted area in the tank when the lights are off dos it open up in the dark

In my opinion you need to eliminate both spectrums. Try it in adjusting light while keeping flow the same, and if that doesn't work try changing flow while keeping the lighting consistent. I took this simplistic approach with acclimating mine and I have achieved full polyp extension and its eating big weekly like a champ.

If yo look at a past post labeled the same as yours "Duncan not Opening" It was started by Conklin and I last posted on it. It appears to be very similar to yours. I have suggested to that mine likes to be high in tank and med high indirect random flow, (yes totally opposite of what the typical Duncan prefers), however mine is doing great and went from a dozen heads to over 30 now. Conklins Duncan was closed for a looong time and he finally put in same type of area and finally opened. You may want to go read that post, I believe I last posted to it on April 24th. These Duncans have very wide preferences. I have read this on many different post . Maybe Conklin can give and update on his

I HAD THE SAME PROBLEMS A COUPLE OF MONTHS AGO WITH MY DUNCAN. I MOVED HIM SEVERAL TIMES AND IT FINALLY STARTED LOOKING BETTER. ENDED UP BEING AN ISSUE WITH WATER QUALITY. I WAS BUYING WATER FROM ONE OF THOSE WINDMILL WATER PLACES. I TESTED THAT WATER IT WAS WORSE THAN MY TANK WATER. NOW IT IS EXTENDING LIKE ITS OLD SELF.