No, I don't and cannot assess that risk. You could spook them first so that they retract. My guess would be that their feeding tentacles are a bit more selective than a mucus net.Do you have any feather duster/fan type worms? Im curious if this will wipe them out too, I have some pretty cool ones.
I can say that the following corals don't mind CaCO3 at all. Even direct shots via syringe.
Acropora
Zoanthids
Scoly and trachy
Tube anemone actually LOVES this treatment for some reason.

.. Thus far the forum lore seems to point to starving them out, but this makes little sense to me then as to why the larger ones remain. Could it be that the process takes more time for the larger ones to die off? or is something happening thats plugging up the tubes with to large of a particle size for the small snails..

