A fresh water dip is not really using fresh water it is more of a hyposalinity dip. There is salt in the water but usually around .015 or a little less if I remember correctly. Fresh water dips are better for sick fish than corals though. I would do the iodine dip as Zoos tend to carry zoo eating nudis. The iodine dip makes almost all unfriendly and friendly critters come off the rock trying to get out. Bristle worms, nudis, bristle star fish, pods, etc come off the rock.
I have several different colors in my tank but the thing that you want to keep in mind is to use gloves when handling zoos. They are poisonous! It's called polytoxin (not sure on spelling) and it can really make you sick. The poison can also be realed in the water if it too close to another coral to kill it and make room so it can grow.