I expect any strong acid or base would knock back the anenome..as does very hot water and very hyper/hopotonic saline. The issue seems to be keeping the overall concentration of what you are using low enough and directed acurately enough to not upset or kill other things in the tank plus the issue that "spot" killing is not getting them all so the population continues. What we do chemically/physically is rather like aiming at population control by eliminating all that go through the doors of starbucks and macdonalds...seems like a lot but in reality only a drop in the bucket
