Green Pocillopora Damicornis becoming white

[bulabr]

Hi Friends

I need your help. My Green Pocillopora Damicornis starting to be white in the middle. It is around 5 inches of diameter and around three years old.

Parameters of my 75G tank, 4 years old

PH 8.0
Nitrite 0.0
Nitrate 5.0
Ammonia 0.0
Phosphate 0.0 by Hanna
dkH 8.8
Ca 450
Mg 1410
Temp 80F
Salinity 1.025
Running one Phosban reactor with Rowa and another one with EcoBak pellets
Scrubber and chaeto in the refugium
Skimmer Reef Octopus

What could be?

Bulabr

 

[bulabr]

No one :-(

 

[Relativity]

Are you using leds

 

[Pittsburgh]

I've lost mine twice due to what I believe was high Alk. Pocillopora was the first one to go in both cases. Keeping Alk under 7.5 dKh seems to be much safer, especially in ULNS.

 

[bulabr]

Yes ... LEDs.