Whitespots On Live Rock

[roboticfish]

Hello,
Recently within the last few weeks i noticed whites pots forming on my live rock. Each one is about the size of a quarter. Not sure what it is from but i recently started using RO water over tap water.
Amon = 0
Nitrate = 80
Nitrite = 0
PH = 8.1
Not sure what calcium is as i have FOWLR and only measure it about once every 8 months. Also i have a huge aiptasia issue with about 15-20 small ones all over.
Thanks in Advance for the help.

 

[bang guy]

My guess is a shortage of alkalinity combined with an abundance of Phosphate.

 

[kiefers]

Hi there.
I was going to ask if there are any corals within a few inches of the white spot but there doesn't seem to be.Go get yourself a few pepermint shrimp for the aptasia problem.
Otherwise, I agree with bang, check you alk and calcium soon.