Some pool stores provide an “adjusted Alkalinity”. By deducting the cyanurate acid portion of the TA to provide an adjusted Alkalinity. Look at the test data & any notes they provided.
Please refer to the TFP Wiki on TA - here is the info from it. You did not post your CYA number but you could be comparing apples to oranges. Furthermore, as others have stated - pool store results are notoriously inaccurate so take there results it with a grain of salt. So if you have the K2006 test kit - ALWAYS GO BY YOUR TEST DATA. Don’t try to compare between pool stores as it will drive you insane
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Cyanurate does contribute to the TA.
Some test procedures say you should deduct 1/3 of your
CYA from your TA to really get a true reading but this in effect is producing the carbonate alkalinity value.
PoolMath accounts for the effect and no adjustment is needed for TFP Methods. Taylor, for example, describes the practice of deducting 1/3 of the CYA value which in effect is removing the cyanurate alkalinity portion to produce the carbonate alkalinity value. Taylor then use this carbonate alkalinity value to calculate their Saturation index (SI).
[4] In practice the concentration of the cyanurate ion is pH dependant where at a pH of 7.0 it is 22% of the CYA. The percentage increases with pH where at a pH of 8.0 it is 36% of the CYA value.
[5]
When cyanuric acid is added to the water, the hydrogen ions that are released lower the TA as much as the resulting cyanurate raises the TA. So, adding cyanuric acid has no net effect on TA. End Quote