One Euphyllia acting strange - need some ideas

[p_lipa]

Hi,
I've got three euphyllias placed next to each other and because of it in very similar conditions. There is no major differences in flow and lighting, however one of them seems to really upset oppose to the other two.

Few heads are going lighter and overall it is half-way closed all the time. The frag come from exactly the same source as rest of them and it was the biggest one . The situation has changed after I've cured the tank with fluconazole. All three of them didn't like the medication, but after several water changes two of them seems just fine. One is not... I've tried a couple of things over last 4 weeks: changing the place a little bit, dip in coral rx, dip in iodine. Right now, it has not been touched for over 2 weeks, but things are not looking promising. Do you have any idea, what might be wrong with it?

Water parameters:
ph: 8.1-7.9
alk: 150ppm
NO3: 2-3ppm(increased with NaNO3, naturally it drops to 0)
Phosphate: 0.05-0.03ppm(increased with NaH2PO4, naturally drop to 0)
Salinity: 34 ppt

Tank is 160gallons, 1 year old. As you an see currently fighting with cyano.

 

[Lavey29]

With virtually no nutrients in your tank your corals are starving to death. They decline from the inside out and can take many months before they show the affects visibly.

 

[p_lipa]

That's well understood and I'm constantly fighting to keep them elevated, but algeas are taking most of it. Do you suggest to try elevate them much harder? If so, what would you target? NO3 10, PO4 0.1?