Reading the TA test results

[My_Hoosier_Pool]

First, I love my new test kit. However, I have a pretty simple but important question that the forum could probably answer. When do I stop adding drops during the TA test? Is it when the water just turns the first shade of red (pinkish) or is it when I have added two or three more drops and the water is a more traditional red? I feel like its a dumb question, but hopefully I am not the only one wondering it.
Thanks Forum.

 

[JasonLion]

You add drops until the sample changes to anything in the red/pink family. Then you continue adding drops until the color stops changing. The final drop, which does not change the color any further, does not count.

 

[duraleigh]

For the TA test (and ALL drops based testing, the endpoint is reached when the last drop you make creats NO FURTHER color change....you then subtract that drop.

For example drop 9- little change drop 10 - tiniest change - drop 11 - no change at all. Now subtract drop 11 so the endpoint of your test was drop 10. 10 drops x 10 + 100 ppm.

PS - somewhat related, when your TF-100 or K-2006 is VERY new, the Reagent used in the TA test (R-0009) can show a tendency to form smaller drops.....skewing your results too high.

Follow the instructions and wipe the dropper tip in between drops with a damp cloth or damp paper towel and that will solve the issue.
This phenomenon goes away at around 10 days more or less from when you first use the R-0009.