chalice coral and acro receding

[Flounder's Reef]

Hello I have 2 corals that all of a sudden started going down hill not sure why. Both are receding and the chalice I used a turkey baster and it look like I blew the flesh right off all other chalice are doing great.

Alk 8.9
Calcium 458
Nitrate 0.0 been this way for 9 months
Phosphate. 04
Ph 8.2
Salinity 1.026

 

[Dilan Patel]

No3 is too low as well as po4 imo for how high your alk is. I personally run at 9kh, ~10pm no3 and ~.08-.12ppm po4. These numbers give me a buffer as I can sway a bit and my corals won’t really show any consequences.