The only thing that I have seen it hurt are the small bristle star's. They act drunk on the stuff, and at that high of dose it may kill some of them. I think you could wait a while, to see if there are any eggs that hatch. I would check the zoa colonies for any egg clusters, they will be shaped in a circular spiraling pattern, small and white. I would watch the zoas very closely over the next couple weeks, if you see any of them closed up or looking funny, I would check for more nudi's, if more nudi's are found, then I would dose with the flatworm exit.