Montipora mollis damage, but what caused it?

[metalruebe]

Hello there,

my montipora mollis has a big white spot/dent in it. It appeared suddenly in a 1-2 day timespan. Any Idea what caused it? No Pests present in my reeftank (not that i know of, used dryrock, dipped all frags in Red Sea DipX before introducing), 1 tomini tang, 6 damsels and 2 clown with hermits and snails is my stocklist. Frag was about 2 weeks in my tank, i use 2 Radion xr30 pro on 90gal. Any Idea reefvets?

 

[metalruebe]

My water parameters are:

Nitrate 7.6
Phosphate 0.067
pH 8.2-8.3
Alkalinity 8.5
Ca 420
Mg 1410

I wonder if it could be burned because of my Radions?

 

[metalruebe]

I transferred the frag to a position near the tank bottom, because i thought its too much light. No critters present after examination with a magnifying glass.

Tissue continues to recede pretty fast
Does no one have an idea?

 

[ryanjohn1]

Dunno what caused it but it’s bleaching out. From what I’ve been told and read. Monti likes high light high flow