Dying coral....very quickly

[ahl]

Hello guys I have a dying starbursts cap and it is happening real quick. It is towards the bottom of the tank under direct light.
No idea what could be, need suggestions before gone.

Tank is in fallow and went through a fluconazole treatment forb3 weeks where I mistakenly turned off the skimmer completely. It's back on now.

Water params are:
NO3- 3ppm
PO4- 0.1
Alk- 8.7
Ca- 425
Mg- 1430

 

[landlubber]

I would attribute it to instability.
you just went through a medication period and you admit your skimmer hasn't been running for 3 weeks. given the brief information you have given, those are two examples of disruptions that the system has to deal with. did you run activated carbon following treatment to remove the medication? montipora cap is an obvious indicator coral in my tank and often displays a present issue before I know its there.
aside from that, sps are sensitive and as forgiving as fluccanozole is in comparison to many other tank treatments it isn't without incident. I used it a couple of years ago to eradicate some bryopsis and lost coral in the process.
imo the only adjustment you could possibly try is to move the coral to an area of higher flow and under different lighting but even so, it'll be 8 weeks before I'd be comfortable that things you can't measure are back to normal after treatment.

 

[ihavecrabs]

I would agree on some instability and high PO4 likely causing the STN.

 

[ahl]

Thank you both! I did move it to a higher flow, hope that stops the fall