Quote Originally Posted by famousdavis View Post
Not suprisingly, everybody's tests read somewhat differently.
Pretty much normal...trust your own readings with the K-2006.

The pros differ from each other on Stablizer.
Once again normal, test it yourself.

The pros differ wildly on Alkalinity. The dropper-based Pinch-a-Penny test aligns well with my own OTO kit and, now, my Taylor K-2006. Those three tests showed Total Alkalinity of 80 or 90. The test-strip-based Pool Store said my TA was 120. They've consistently give TA results much higher than the others.
That is one of the big reasons we don't much like test strips with or without a strip reader!
BTW, the OTO kit says free chlorine can be measured by watching for results a few seconds after dropping in the reagent. Waiting 5 mins or so gives a Total Chlorine reading
Wrong Wrong Wrong. OTO tests Total Chlorine. Period!

Pool Store said I had almost no free chlorine: 0.2, with no Combined Chlorine. Pinch-a-Penny said I had 1.0 Free Chlorine, no Combined Chlorine. So, Pinch-a-Penny and my own OTO kit are pretty much in agreement.
Pinch a penny uses Taylor reagents and does DPD testing which is pretty much like OTO except that it will test for FC and TC, unlike OTO.
My Taylor K-2006, however, reads quite differently. The Taylor kit read 3.5 for free chlorine, and some trace level of Combined Chlorine (I say "trace" because during that part of the test, the water color was a very slight shade of pink, but turned noticeably clearer when I added that one drop of reagent that calculates CC).
Count the drops it takes for it to turn colorless. The intensity of the red does not matter. The number of drops it takes to turn it colorless does.

During the free chlorine test using the K-2006, I'm adding drops until the water is *perfectly* clear, where no changes in water color are observed. What that means is that the last 2 or 3 drops of the reagent are changing slightly the shade of pink I observe to an even more slight shade of pink, until the point where the white dot at the bottom of the tube is perfectly white, and I can't observe any further color changes.

So here's the question: When I add the reagent drops to the K-2006 that change the water color from pink to colorless, is the objective to really get it to be 100% colorless, or just mostly colorless with perhaps a slight tinge of pink still remaining?
100% colorless. The test is to keep adding drops until one more drop produces no more color change and then don't count the last drop. It's really pretty easy.
How colorless do you strive to make the water during this test?
Once again, colorless.
If I just went for a big noticeable change away from the pink color, I probably got that within the 4th drop of the reagent. But I had to go to 7 drops (7 * 0.5pppm = 3.5ppm) before it was 100% colorless.

Thoughts?
If it takes 7 drops and an 8th drop produces no more color change then 7 drops it is!
I'd like to use Pinch-a-Penny for a "professional" tester that can provide backup against any warranty claims I might need to make in the future against my Diamond Brite pool finish).
That is fine but I would not follow their dosing recommendations for pool chemicals. Remember that they are in the business of selling chems.