What's this purple ring on hammer coral?

[ace1396]

Alright so here the specs
55gallon 6months old going through ugly phases
ÑO3 undetectable (API)
PO4 1ppm (API)
SG 1.026 (refractometer)
78 degrees
Ca 500 (salifert)
Mg 1380 (salifert)
Alk 10dKH
PH8.3
T5s (11-7) daylights
2t8 (9-8) atnic and 50/50 10k atnic
Rodi ATO
8gallon/week water change reef crystals

A few weeks ago we got a torch frag, acclimated and added to to dt. After about a month we woke up and 1 or the 2 torch polyps was gone over night. Next day the other polyp was gone. So I removed the frag from the tank and inspected it. No visable bjd or any other suspect.

A few weeks later my hammer who is on the same rock structure stops fully extending. He still opens up to some but not fully extending. Stays closed up a lot more now. All other corals look fine so I'm thinking it's euphyllia specific, and did a fw dip to see if any polyclads or other uglies fall out. Well when the hammer recedes I noticed a spot on the skeleton. Any ideas?
Could this be what killed the torch and is working on my hammer?

 

[norfolkgarden]

Dry rock goes through a number of stages. Takes about 8 months. Kind of early for coral without even a little already cured live rock in the tank. Even for something as easy as hammers.

Do you have anything like a snail shell or small rock already in the tank with coralline algae on it?

Once the coralline algae starts taking off the dry rock should be finished curing.

 

[Tuffyyyyy]

Do you run any blues? Whatever you have growing in the back looks pretty happy, so I'd guess it's something euphyllia specific.

 

[ace1396]

Dry rock goes through a number of stages. Takes about 8 months. Kind of early for coral without even a little already cured live rock in the tank. Even for something as easy as hammers.

Do you have anything like a snail shell or small rock already in the tank with coralline algae on it?

Once the coralline algae starts taking off the dry rock should be finished curing.

The dry Rock was in my cichlid tank for about a year before I started the reef tank I do have about 3 lb of live rock in the tank also

 

[ace1396]

Dry rock goes through a number of stages. Takes about 8 months. Kind of early for coral without even a little already cured live rock in the tank. Even for something as easy as hammers.

Do you have anything like a snail shell or small rock already in the tank with coralline algae on it?

Once the coralline algae starts taking off the dry rock should be finished curing.

The rocks now have green and white calcerous algea growing on them right now. No purple or pink yet.

 

[ace1396]

Do you run any blues? Whatever you have growing in the back looks pretty happy, so I'd guess it's something euphyllia specific.

These are the t5 bulbs
The t8 are 1atnic and 1 50/50 10k/atnic