First, let it be known that I have color vision impairment, so I don't trust myself to do my own testing.
That said, I have been using two pool stores to do my testing. One of them is Leslie's, and the other is an independent called Cal-West that primarily sells spas. I have also been using an Aquachek TruTest digital tester to do my day-to-day FC and pH measurements.
The problem is that the two pool stores have been getting different results for certain key tests.
Leslies: CYA 25ppm
TA 130 ppm
Calwest: CYA 40 ppm
TA 60 ppm
Leslie's uses their standard reagent testing, while Cal-West uses an automated test strip reader made by Hach. In each case, I've had the water tested within 20 minutes of each other.
I like the idea of taking the (possibly poorly-trained) human tester out of the equation, but I'm concerned about the accuracy of the automated tester.
Which set of results should I trust? Any opinions?
~13,000 gallon pool (no spa)
520 SF cartridge filter
white quartz plaster
Pentair IC40 SWG