Received my new TFTest Kit last week and finally was able to perform my own CYA test. The pool store had tested at 100. Before emptying and refilling, I wanted my own well measured test results.
When I first tested (Thursday) I felt comfortable with my results (80); but when I returned from vacation today (Wednesday) and retested, the results came in at 90.
Only acid has been added between those tests so I'm a little confused as to why the CYA would have gone up.
Wanted to ensure I understood how to read the results just in case the issue lies there. It seems like the test could be read differently depending on one's understanding and visual (20/20) limitations.
The instructions state: "Keep filling until the black dot in the bottom of the tube is completely obscured."
Does that mean that the black dot cannot be seen at all, not even a ghosting of it?
I also thought I read in some posts that temperature of the water and wiping the dropper bottles produces more accurate results.
Is that correct and can someone expand on the whys behind them if so?