Tyler, GSP can be a PITA to control. I made my own Kalk paste to Nuke it. worked like a freaking charm. and would knock back anything I put it on.
take a Microwave safe saucer or bowl and put a 2 tbsp of pickling lime in it and enough RO water to make it like toothpaste consistency. then add a tsp of crushed red pepper and some hot sauce like Tabasco. Microwave till its bubbly hot then stir it up. add soem water to keep it like toothpaste consistency. it cannot be watery or it will not stick to the intended victim. then spoon it into a syringe and squirt away. it is reef safe (dont get it on coral) and kills it off very well, just tastes like sh!+. Ive used it on GSP, Pavona, Apistasia, Mojanos and Tulip anems. on the nems, just put a drop in their mouth. they melt away in a matter of an hour or so. also, if you attack a section of the GSP, it will all close up.