You can also pick the spiral shaped egg cases off of the zoa polyps; easy to see out of the water with a little actinic; tweezers worked for me. I'd get a start on it ASAP!!!!! I personally think a freshwater dip is just as effective as "treated" water for nudis. They just disintegrate or fall apart in a matter of seconds. The iodine (Lugol's etc.) is good for the zoa polyps as well as being "toxic" for critters.

Mike, what species is your green coris? pics?