Fresh water dip!
I use distilled water but don't do it for to long,
Distilled water will make corals go hypo and can kill them if they sit it in for to long.
Softies I do 2 mins and sps 5 but I move the water to try and get it off as fast as possible.
The other thing u can do is after take a towel and wife them carefully and try to wipe it off,
You can leave them out of the water for a few mins as well
zoas can last a while out of water as were most desiese wont last so a little air drying wont hurt your Zoa