You might laugh, but I swear by this method for big ones. Get a coffee cup with tap water. Nuke it in the microwave until its boiling. And I mean boiling even AFTER you take it out. Then get a syringe with a fine point or a needle and just spray the heck out of the aptasia. They melt pretty quick if the water is hot enough. I would do this with my 75g and it worked great