Questions about Duncans

[Dgunn]

Hello all, I don't post much but I could use some advice on Duncan corals.

I have a large colony of Duncans that have been in my display tank about 50 to 75 heads. and they have stopped opening.
The Duncans have been fine for about 8 months until the last month or so.
I have a frag tank that is attached to the system in the basement that has some of the same colony that are opening just fine.
I swapped some of the display coral with those in the frag tank and I got the same result. The large colony from the display is now beginning to open and the smaller colony (25ish) stayed open for a couple of days and are now closed up.

The display is a 120 that is lit with 4 t5 aquablue and 2 Kessil 360we.
There are other lps in the tank that are all fine.

I have tried changing the lighting, length of time that the different lights are on and the flow.
The frag tank is lit with 4 t5 aquablue as well.
most of the corals in the display are in the frag tank as well and the tanks are connected together.

Any ideas?

 

[Dgunn]

T5's on both tanks are Blue plus, not aquablue.
All of the bulbs are about 6 months old.
The display has hammers, torches, frog spawn, a large elegance, an RBTA, and a few SPS.
all of the other corals are doing well. The large Duncan colony was on the sandbed front and center,
the smaller colony I put in a back corner where there is less light.



smaller colony from frag tank after 4 days in right rear corner

large colony now in frag tank opening up after 4 days