Have read that an internal filter like a viaqua internal filter place in the tank near the dino will help to eliminate it. "What you need is a powerful in-tank filter that you fill with fine filter floss. That's it You must clean (or change) the filter material each day so that the dinoflagellates won't die inside the filter and poison your tank. wouldn't necessarily recommend doing a lot of water changes because each water change can potentially bring in micro nutrients that the dinoflagellates need. (note: not necessarily the big three, nitrogen, phosphorous and silicate but for example iron, copper etc.)"
This is anecdotal to be sure, however for a $15.00 filter and some floss definitely worth a try in my estimation.