Elegance coral dip/treatment?

[Thawman]

Transferred from a 40g to a 100g. Have had the elegance just over 1.5 years. Initially was PO'ed going into the new tank then seemed to settle out.

Now over the last 2-3 weeks I'm seeing some tissue recession.

1 week ago did a Revive, Iodine, and a Chemiclean dip. Appeared to be healthy afterwards, then yesterday noted some tissue recession in one spot. Will dip again today.

Any thoughts on what may be happening or how to treat it?

PO4 0.025
Nitrate 12
Salinity 1.026
Other params in first pic.

 

[Spare time]

You may have 0 phosphate.


You could do another iodine based dip if you think it is an infection. I like to give sick corals something like reef energy or vitachem too.

Do you see anything around it, weird slime, etc.?