I took a sample of my pool water to get tested at the pool store and they told me my CYA was 100. This is a new pool this August and I bought the Taylor 2006K kit and measured the CYA with it when I got home from the pool store and the black dot does not disappear until I am overflowing the tester. This means that my CYA is less than 20. How could there be such a difference between what I measured and what the pool store measured. I just bought the kit in August from Leslie's. Could my reagents in the test kit be bad, or does the pool store have no idea what they are doing ? Which should I trust, the pool store or my test kit ?

Thanks