My local grocery store has a generic 6% bleach on sale for $1.19 gallon. They have a couple pallets full of boxes sitting out on the floor. My 27' round AGP will be set up within the next few weeks. Is there any way to guestimate how much bleach I might need for the season, figuring part of June, July August and maybe part of September. (Kind of depressing to think about how short the swimming season is in Wisconson). Is there any way to just approximate the weekly or monthly usage? Does bleach deteriate in unopened bottles? Would there be any downside to buying a lot at once to be used over several months?