I know that the shelf life for photo chemistry is pretty short once it's mixed, but what about the concentrate that you mix it from?
I'm going to the store tomorrow to get some D-76 & fixer, but I still have some stop bath concentrate, as well as photo flo. I know I can use water, or vinegar as a stop bath, and photo flow isn't needed either, but I'm curious. They have been stored in a cool dry place, away from light.