Jandy SWCG's "optimal" water conditions: why raise CYA?

[famousdavis]

So I tested my water today, 24hrs after adding more CYA in my pool. CYA is now 80. I tested my FC today, too. Instead of losing 0.5 or 1 PPM like I have been with my current settings (50% for 8hrs), my FC actually rose 0.5, to 5.0. And today was a full-sun kind of day, too!

I may tamp down my SWCG to 40% tomorrow and see what happens. I want to stay near the 4 PPM range.

I get my water tested by the two pool companies tomorrow, too. I can't wait to compare my results again with what their test results say! After tomorrow, I may just release the one company that uses test strips from doing my pool water analysis -- I think their test results are way screwy, especially with my TA and FC levels. Pinch-a-Penny's drop-based testing more closely aligns with my own testing, though last week they came up with a much lower FC level than what I came up with using the K-2006.

[famousdavis]

So I took two water sample from my pool this morning, gave one to The Pool Store (test strip testing) and one to Pinch-a-Penny (drop-based). Plus I did a few tests with my K-2006. Results:

FC
The Pool Store: 2.3
Pinch-a-Penny: 3.0
K-2006: 4.0

CC - everyone agrees, there is no CC

pH:
The Pool Store: 7.9
Pinch-a-Penny: 7.6
K-2006: 7.5 (yesterday's reading)

TA:
The Pool Store: 150
Pinch-a-Penny: 140
K-2006: 90

Ordinarly, The Pool Store has read way higher than Pinch-a-Penny, so I was surprised at today's high TA from Pinch-a-Penny. I was also surprised at their recommendation: that I add 1.3 gallons of muriatic acid into my pool! However, I watched closely the testing process at Pinch-a-Penny this morning. The gal had to run the test twice because the first time her TA reading was, I guess, astonishingly high. During the second test, the reagent she added that turned the water from green to pink resulted in only a slighly higher reading than the "Ideal" markings on her big test tube that measured the amount of reagent she was adding (Pinch-a-Penny says "Ideal" is between 80 and 120). Clearly, there was an imprecise testing process at work that led to the wide discrepancy between her two tests! And even though her second test showed high TA, I did notice that she tended to add a few more drops of reagent even after the water turned from green to pinkish-red. After her high reading, I went home and re-tested TA using my K-2006. I noticed that when I test, I do so MUCH more slowly and deliberately. And I stop immediately after the water turns from green to pink color (the 9th drop of reagent changes a blood red color to pink). Pinch-a-Penny uses Taylor reagents, too, but their setup is different where they measure reagent from a test tube that they're adding to the swirling water, whereas I am counting drops of reagent. I think the speed with which they perform their test compared to my own testing explains the differences in our results. I'm also confident that my reading is correct because I used their last week's TA reading (80) which also matched the K-2006 reading for last week to add just enough baking soda to get to about 90-100 PPM (this was before Waterbear's advice to keep the TA at the low end of "Ideal").

CH:
The Pool Store: 300
Pinch-a-Penny: 350
(I didn't test this since it's been stable since I got our pool)

CYA:
The Pool Store: 75
Pinch-a-Penny: 80
K-2006: 80

CONCLUSION: I think I can now test my own water using the K-2006 as well as the "pros" at Pinch-a-Penny, and I can do a decidedly better job of testing my own water than the test-strip folks at The Pool Store. So I'll "fire" The Pool Store and move to less frequent visits at Pinch-a-Penny, just to ensure I maintain the warranty requirements on my Diamond Brite finish. And I'll trust my own judgment -- and the judgment of this forum -- more than the advice I get from Pinch-a-Penny.

A BIG THANK YOU to this forum! I feel like a Pool School graduate today. :-)