I have read the Ascorbic Acid article in Pool School and I have also read the long 7 page thread (which is now closed) laying out the steps to perform this treatment. So no need to direct me there.
My confusion is: When I lower the FC level to near 0 so the Ascorbic acid doesn't get eaten up, the instructions calls for adding Polyquat 60 to prevent algae growth during this period of no chlorine levels. I get that. But it doesn't state how long I can let it go like this for. Will the Poly 60 protect me for a day, a week? etc?
The idea of letting my Chlorine go to zero concerns me. Now I am in NJ and plan on closing pool in a few weeks anyway. But I understand an effective AA treatment can take anywhere from a few days to a a week to work. And then I have to SLOWLY - not shock the pool back to proper FC levels. So that could take another week or so.
So will the initial Poly 60 treatment be enough to last this whole time? Or should I continue adding Poly 60 on a "maintenence basis" while my FC is zero?
FYI, the reason I am considering doing this is to once and for all try to rid an area in the deepest part of the pool of a stubborn stain that has been there for a few seasons.
Note to moderator: I put this in the Algae section because of the questions regarding Polyquat 60. If you feel it belongs elsewhere, please move to appropriate place. Thanks, Mike