Algae on tips of coral

[jfenton954]

Hi I got home from work yesterday to see brown algae on my blue acro. It's in high light at top of tank with high flow.
The polyps don't come out anymore I've noticed. Not sure if that's good or not I'm guessing not but not sure.
Nitrate 0
Amm: 0
Phos: 0
Alk : 7
PH: 7.8
Cal: 450
Mag: 1200

 

[jjoos99]

algae on the tips means the tissue on the tips has recessed. Not good, not really sure why. I have a sertosa that has the same issues but all the other corals look great.
Jeff