They are the fastest spreading pest I have found in my tank, with in a couple of days they had sprouted up on almost half of my rocks. Get rid of them ASAP. I hear they also have a light sting when in a good sized group.
I've actually heard of people taking a torch to them, probably a little extreme and harmful to other life form on the rock but probably satisfying with how much of a pest they are.
I actually electrocuted mine by accident (heater shorted out), that worked. But if I had a choice I would go with your method though Randy, that sounds most efficient.