With a tank completely over run, using any injection method will probably be a waste of time.
Depending on the size of your tank, and other tank mates, some possible treatments would include:
Berghia Nudibranchs (may be eating by some types of wrasses) You'll need to research these to decide if it's the direction you want to try. You need to make sure you start with a large enough group of them, or they won't work.
Copperband Butterfly (if tank is large enough) Make sure it's eating prepared food, at the LFS, as that's the most common difficulty, with these guys.
Matted Filefish (Acreichthys tomentosus) Make sure this is the species you get, as a lot of filefish species share common names. These are "somewhat reef safe." In the several months of research I did, before purchasing one, to eradicate my Majano problem, I found that about 40-50% of people have found them to go after Zoanthids, AFTER eating all Aiptasia and Majanos. The other 50-60% have found them to be completely reef safe. I've had one for about 3 weeks now. It's doing a great job on my Majano anemone, and so far, ignoring the hundreds of Zoanthids I have.
