Kill all the big specimens with
kalk paste, no more than about a tablespoonful in 30 gal a day (remember tha kalk can be a bit of a problem if you use too much) Forget Joe for a while if they are all big, then release the peppermints. They will kill little ones much easier than th big ones, and do not feed the tank heavily for a few weeks unless you have fish that must be fed on a daily basis, then just what they will take up in the 5 minuts r s you stand and watch. This keepis you from feeding the peppermints at all, so they will go after the aiptasia.