Well, I flush for the last week or so; but I'm not concerned with chlorine much which is what pool shock is. I mean it's chloride ions which are natural and healthy when kept in balance. And, I like the fact that I'm using something natural to disinfect with. It's cheap, it's widely available, it works extremely well and it's a natural ion despite it's synthesized. I do see your point but I don't find chlorine much of a threat as oppose to some of the other chemicals that are sold. Besides, without the chloride ion we'd still be dying of dysentery.