First I am not an expert, but from everyone that I am asking you have to have a sanitizer in your pool, i.e. chlorine, bromine, or baquacil. Second I have a customer that is allergic to man made chlorine, but is fine in a swcg system. I also have a customer that is wanting to do a copper system and not sure I can do that as there is nothing to kill bacteria in the water just using a copper system.