I'm a firm believer than Dinos are in every tank. Balance and stability is what keeps them in check, especially when it comes to nutrients. I have always beat them back (never eliminated them, but as far as they are no longer visible or harmful) with a combination of nutrient stability and UV. Some strains are more difficult than others.
I would cure the rocks in a tote or bin and add beneficial bacteria and food if you are considering external treatment, but the dinoflagellates will survive in the main display anyway.
Best way to beat Dinos is to get your tank stable with some nitrates and a little P04. Removing the rock and treating it with anything will only clean the rock temporarily. Once it goes back in the rock will get covered all over again.
You can add a UV sterilizer to your tank to help as well.