I use a melanarus wrasse . It is always hunting and picking at the zoas and other corals for food.
http://www.themarinecenter.com/fish/...lanuruswrasse/
I alos dip all my zoas when I get them an expect them for eggs. I use the salt water they came in and 5 drops of coralRX. It kills all inverts and nudis that are on the frags and colonies. I have a friend who swares by flat worm exit. Same thing adds it to the water they came in.
http://coralrx.com/
If you can remove your colonies and dip them and expect them I would.
Chris