Zoas bleaching. Any ideas?

[FossilReef]

Alright, so this seems to be sweeping through my zoanthid population, affecting even the mighty P. grandis. They've just been bleaching out and wasting away to nothing. My params are all normal, nothing new has been added, and I did check for nudis, nothing. I'm really having a hard time tryign to figure this one out, as it doesn't look like zoa pox. One day the polyps are fine and the next day they're bleached. This isn't happening all at once, it's slowly spreading. Lugol's dips have done nothing, and upping my water changes has had zero effect. Any ideas people? My tank is 70% zoas, so anything would be helpful!
Thanks,
Jason

[Daniel]

Does it look like anything in this article?

http://www.zoaid.com/articles001.php

[Obi-Wan the Goby]

Post a picture if you can; that always helps.

Have you been doing any vodka/carbon/vinegar/sugar dosing to lower nutrients? How old are your lights?