Carl, I don't know if I am wasting money or not, but I have started replacing all my chemicals on my Taylor 2006C test kit for just the reasons you point out above. I don't have a lab here at the house to test my supplies to ensure they will give me accurate results. Since it is not "that" much to do it, I replaced them all. Testing accurately did so much to enhance my pool experience last year, I cannot feel good about operating the pool unless I KNOW my chemistry is fresh and right on.

Bob E.