Brown spot on Setosa

[xwnti]

I noticed 2 large brown spots develop on my Setosa yesterday. Any idea what might be causing this?
I have been adjusting my lighting recently but i don't think that's the cause. Hoping it's not STN :(

My parameters are:
Temp: 74
PH: 8.4
Salinity: 1.025
Ammonia: 0
NO2:0
NO3:10
PO: 0.1
Alk: 9
Mg: 1385
Cal: 500

 

[Mastiffsrule]

How are you,

I see what you are saying. I’m not thinking stn. I’m inclined to think it may just be the angle it is getting light. Is that are growing in the shade?,

But, I would like to get other opinions. My ID on coral is not my strong point

 

[Graffiti Spot]

Looks like something damaged it and algae grew over the dead area.