Thank you Both! chem geek, that is a great explanation. The sanitizing action is almost counterintuitive for me so pardon the repeat question. I am glad I have a normal pool. I also vac by hand and take a few extra minutes each time to do stair fronts, side walls and and the like. Those areas get done maybe a little less than 2X per month where the pool is vacuumed every week, at least. This is an important caveat in understanding sanitizing. Thanks again!

Paul