This is an old post, but I see people suggesting boiling water and Lugols iodine. I use a kalwasser paste to eliminate aptasia, unwanted zoas and cloves such as this. Mix to a thick liquidy consistency and put in a syringe with a large bore needle tip, apply to the undesirable with the pumps off. Wait 30 minutes and restart the system. Make sure you don't get it on the corals you want to keep. As the pumps come on some disolves into the water, but that just adds some calcium and doesn't effect other coral.