In all cases (brands, stores, strengths, etc) is it (has it been) ever possible to buy bleach that has something other than sodium hypochlorite that was not indicated on the label? In other words, if I read the ingredients and only sodium hypochlorite is listed (other than water or whatever the inert ingredient is), then is it safe for my pool? Any brands sneaking in stuff we don't want, hidden from the label?
While I can figure out the expiration date from an internet-available calculator, how about adding some sort of calculator for chlorine age to Pool Math (the app and the web page)? For the app, there's a big ol' space right under the Price calculator, just waiting for such a thing!