What is this white patch?

[MONTANTK]

My acro recently developed this white patch. I had a birdsnest which developed a similar patch which resulted in tissue loss. Any idea what it is? I don’t notice any pests and it doesn’t necessarily seem to be spreading.

Alk: 8.4-8.6
Ca: 420
Mg: 1320-1350
No3: 2ppm
Po4: .01ppm

 

[Perry]

Zooxanthellae concentration or lack thereof, the coral is getting more pastel as a result of low nutrients. The coral looks otherwise healthy, but a lower kh concentration and a tick upwards of nutrients will bring more saturation to the coral.
My best guess :)
Cheers

 

[MONTANTK]

Zooxanthellae concentration or lack thereof, the coral is getting more pastel as a result of low nutrients. The coral looks otherwise healthy, but a lower kh concentration and a tick upwards of nutrients will bring more saturation to the coral.
My best guess :)
Cheers

That seems to make sense. I’ll keep trying to raise nutrients since it’s easier than lowering Alk