I have a slightly conflicting drop count. As per a NJ reefer member
I've seen it at pharmacy's near the band aids and such.
To dip, use a 5 gallon white bucket if you are going to dip a lot of corals. The white bucket will allow you to see what is going to fall off the rock. Fill it half way with RO water. Set your temp at 78 degrees. Set the PH at 8.2 to 8.4, which is where your tank should be as well. Add about 2 drops of Lugol's per gallon. I also add 3 drops now of Flatworm Exit to the dip. Now place 2 or 3 rock in the bucket and leave it there for 5 minutes. I have stepped my dips up to a full 7 minutes for the past several months with no negative affects at all. After 5 minutes, grab the rock, invert it facing the bottom of the bucket and while still submerged, twist your wrist clockwise and counterclockwise as fast as you can. Do this for 1 full minute if you can. You will begin to see things flying off as well as some debri and sand. Raise the rock out of the water and dunk it face down in the water to finally knock anything off that didn't dislodge from the rock. Place it back into your system and your done.
His comment is for rocks, but I don't see the difference.
rich