What's Wrong?

[beej210]

So I just noticed today that my frogspawn and Duncan are very unhappy. Frogspawn looks like one branch is almost completely dead. My alvepora, zoa, and branching hammer are all just fine.

Tank is 3 months old - current readings are:
Salinity - 36ppt
Ammonia - 0
Nitrate - 7.5
ALK - 8.93
Calcium - 377
Magnesium - 1370

All my numbers are pretty consistent. My ALK has been rising from 8 to 9 over the past 5 days but I was intentionally trying to bring that up. I'm not dosing calcium and it's been very stable around 360-380. Last night I put a tiny bit (less than 10ml) of PNS probio into the sump. All fish seem healthy.

What is happening to these 2 corals and what should I do to fix it? And is the frogspawn dead - at least that branch? Is this recoverable?

 

[allof fish]

Could be bacterial. Do you see any issue around the polyps or any bjd. I would try to raise calcium a little. What’s light and flow like? The frog spawn has bailed that polyp out unfortunately that one it dead but as long as it’s not bacterial the rest of the colony should be fine. You can snip it off as a precaution and I would recommend that

 

[Rocks reef]

Stability comes to mind. At 3 months, the tank is still new and will take time for find it's balance.
It doesn't look bacterial.
What is your Phosphate?