I have no idea how.. I haven't added anything to the tank in atleast.. 4 months. Must've been here all along.. It says to manually remove. I guess I'm going snail hunting. I was wondering why my AOG's looked like crap. Anyone have any other tips on removal? Some kind of dip? I did start using my reef dip to see if it has any effect. (I bought the AOG from BR with 3 polyps. It's now on a tiny plug and has probably 30 heads. Hopefully I can save them. (sorry for the run on, I am now sad)