So I'm into my 8th week of pool ownership. Up until yesterday, I was using my Pinch-a-Penny Basic Test Kit (OTO) to test for chlorine and ph. Over these weeks, the chlorine readings are either a solid 2.0, or maybe a little lighter shade, but not the shade of 1.0 (so I marked down 1.5).

I've also been pitting two "professional" pool companies against each other: a local Pinch-a-Penny store, and another store called, simply, The Pool Store. Pinch-a-Penny appears to rely on some dropper-based testing. The Pool Store relies on a computer and a test strip.

Then yesterday, I received my Taylor K-2006 kit.

Not suprisingly, everybody's tests read somewhat differently.

Among the pros, the points of agreement are with Calcium Hardness and Salt. I couldn't test for these without the K-2006, so that's fine.

The pros differed somewhat on pH testing, but not significantly, and their tests were fairly close to my OTO kit anyway, so that was fine.

The pros differ from each other on Stablizer. (BTW, I take pool samples from the same pool location at the same time, and then turn the two respective bottles over to the pros for evaluation, just to see what they both tell me). But since it's a matter of one pro saying I've got 45 and one says I've got 65 (as was the case today), but both are fairly good numbers, I've not worried about it.

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.

But it's testing for chlorine that most puzzles me!

This morning, my OTO kit showed I probably had free chlorine of 1.5. (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). 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.

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).

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? How colorless do you strive to make the water during this test?

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?

(I'm about to free myself from testing at The Pool Store, as their tests seem to be mostly the outliers and probably inaccurate to a large degree. 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).