I don't understand the pushback against electronic meters and "calibration"? It's much more accurate, precise, and not to mention faster. In the lab, you'd be hard pressed to find someone using a drop test or litmus paper to properly measure pH. The electric meters are pretty reliable. I find it easier to just press a button and read the pH then trying to compare colors under same light after doing the drop test. I can test my water in 2 seconds and only need enough light to read the LED screen. I bought just the simple one from tftestkits and it's been flawless after a month of use. Right out of the package required no calibration, and it's still spot on. I bought some calibration fluids from amazon to test it weekly, and it's never drifted yet. Though just being used for "neutral" water the drift on the electrode should be quite minimal through time.
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17.7k gal, 98 ft perimeter, IG quartz, 3HP EcoStar VSP, 1.5HP TriStar Dual Speed, 725 sq ft SwimClear Cartridge, Rainbow chlorinator, Paramount clear O3, Pro Logic controller, 500k BTU heater, AquaVac 500, Spillover Spa, 3 sheer waterfalls, 3 bubblers.