I'd stick to a proper coral dip. Seachem Reef Dip has iodide in it.
Back in the dark ages, before commercial coral dips, we used to use Lugol's Solution (Iodine and very concentrated) to make dip.
Reef Dip takes the guesswork out of how much to use etc.
Oh and one other thing. If the plate takes the eternal dirt nap, leave it in the tank. Often, new offspring will sprout from the dead parent's skeleton.
Jenn