Understood, and the higher the concentration the quicker it deteriorates so that should be taken into account also.
I did not know that. I also learned here that the expiration date isn't even the whole picture. It has a lot more to do with
where the chlorine is stored, and where it's
been stored. A pallet of chlorine that was left on a loading dock somewhere for a few days in the hot sun is going to be a lot worse off than one that is months older but has been kept cooler. So you never really know what you're getting.
I sometimes buy my chlorine at Leslie's, taking advantage of the coupons they bombard my inbox with, on the fantasy assumption that they go through stock faster than my Lowe's does, and so might likely have fresher stuff. And they don't have a loading dock, or outdoor pool department, so at least once it's delivered it's stored properly. But, again, I don't really know that.
Point was... in addition to price, you also have to shop with the quality of the handling of the product in mind...
Yet another reason to test your water yourself, often, and not rely on calculators or pool guys or suppliers, who ignore such things.
Also a plug for an SWG. Overall cost compared to chlorine is pretty much the same. Eight months out of the year I won't have to think about chlorine, let alone shop for it. And it's absolutely the freshest chlorine in town!!