Branching Hammer Retracted

I have a nine head branching hammer colony that I have grown from a small single head frag. The frag has not moved in months, no new additions, lighting hasn't changed, and the tank is over two years old and holds everything from acros to zoos. Only thing that has changed recently is the pump died on my carbon / gfo reactor that I haven't replaced as of yet, but is in the mail.

Over the last week the polyps on three of the heads have been really tightly retracted. At first I thought it was expelling but it lasted more than a day or two. I don't see any brown goo like brown jelly disease. I have acans and a frogspan that all look good. Other coral also looks great.

All the parameters I test for are listed below. Tank is a 150, DIY LED fixture, the colony sits about 175 PAR. Any ideas?

Temp 78.2
Ammonia 0
Nitrite 0
Nitrate 0.5
DKH 8.82
PH 8.2
Salinity 1.025
Calcium 440
Phosphates 0.05
Mag 1320
Strontium 7

 

Is it near any other corals like frogspawn or torch? My frogspawn and torch will randomly retract when a fish grazes them at times and other times they don't care.

Your parameters look fine to me.

 

The closest thing is a Platygyra brain but it's on the good looking side, about five inches away. The nearest thing on the retracted side is an acan but its a good eight inches away and elevated. I took this today since the lights were off last night. I cant really get a picture around the back where it's bad, but you get the idea.

 

Maybe try rotating the entire colony 180* to see if anything changes.

 

I rotated it today, we'll see.