Nuke 'em with the KW, but don't expect that to eradicate them. They'll come back, believe me. As Richard said, it's a good idea to take the rock out, then kill them, then "cauterize" or burn the entire area of the rock they were occupying, and try to remove every trace of the dead anemone.

As far as natural control, the best hope is the bergia nudibranch. however, you have to culture these critters, and then introduce rocks with aiptasias into their tank. Just putting a few in your reef will probably not work; they'll get eaten by a fish or shrimp or hermit.

Come on, MAAST members! Who's going to culture these nudibranches for the club members? Somebody step up!

Matt