Burger I also use hydrated to kill limited shoreline FA (guys don't try it unless you know how from a prior thread) and to raise conductivity (if needed) a couple days before the shock boat comes. You do have to be careful with it and know what you are doing or you may kill your fish. If you have drained down a pond that has low alkalinity to a small size you can use it in place of rotenone to kill what is left..