Oh, if there isn't algae in the tank and it came in on the frag of course there is still algae on the frag. Pull out what you can. Scrub it with a toothbrush if you can. If all else fails, you can do a 10:1 water:hydrogen peroxide dip. Zoas won't open up for a couple of days, but they should. I did it and thought I killed the zoas, but they came back around.