Bleached acro polyps?

[mic209]

What do you guys think would cause bleached polyps? I have several across and the polyps are either white or green the rest of the corals have great colors. A couple acros with white polyps included a pink lemonade and a red planet.

 

[nex64]

How long have you had the bleached corals in your tank?

 

[mic209]

How long have you had the bleached corals in your tank?

They're not bleached corals, only the polyps on a few acros. One has been in there for close to 10-11 months. I'll get some pics when I get home. Other than the white polyps, everything is doing great and growing well.