I did a full testing this morning around 6:30 a.m. and also pulled a sample to take to the pool store to test. All the numbers match up close enough except the CYA number (see picture attached, my results are written in pencil). I am getting a reading of 40 and the pool store got 0 . How can it be that different? They were using the Taylor test kit as I saw the cylinder with the black dot on the table where they do the tests (and also after I questioned the difference) the guy mentioned they are using Taylor testing and it is accurate. He seemed surprised when I told him I am using the same kit at home and explained to him how to run the CYA test.
My other question is, I took the sample at 6:30 am but did not take it to the pool store until around 12:30 pm. I left it in my car during this time---could the heat inside the car eat up that much CYA? Am I running the test wrong at home? As a backup in the past I have had my wife run the test and she gets just about the same as me. I will do that again tonight to make sure.
Any thoughts or theories as to what can be causing this huge discrepancy in the numbers?