CYA testing problems

Of all the Taylor tests, the cya to me is the most subjective. (ph being the second but much easier) To me the problem is when does the dot really disappear? I know that may sound stupid but it does get very hard to see before I assume it totally vanishes. I called taylor and they said "when you can see it anymore."

I think my issue is I still need more cya. The best I can make out, it's just below 30ppm. I have added some liquid pricy stuff from Leslie's Pool Supply. I then added 2 4lb bottles of dry cya. (from Lowes - age of cya uncertain does it weaken with age & storage?) To my 14400 gallon pool. My CL seems to be stable overnight but during the day I will loose about 2ppm. Would getting my cya closer to 50 help? Currently I'm using straight bleach but last year I reverted back to a combination of pucks and bleach.

A few years ago I had a very high cya level (around 120?) I drained the pool half way and got it to be around 50 - 60. The beginning of this year I checked it (same kit) and it was barely hazy (well below 30ppm) That sounds impossible because Iv'e heard cya just can't disappear.

I moved your post to its own thread, since your issue was a bit different.

There's no question that the CYA test is the least precise of all -- and that's true of all forms of CYA testing. Strips make the test 'easier' but are horrendously inaccurate, and often can't distinguish water with 10 ppm CYA from water with 60 ppm CYA. The expensive ColorQ Pro photometer is sometimes nearly as accurate as the much less expensive K2006 . . . and sometimes not.

Watch the Taylor videos; they do help:
http://pool9.net/tk-guide/
http://pool9.net/tk-interfere/

A couple of other tips:
+ Do the test outside, holding the CYA test sample at waist level, as you look down.
+ Do the test when the sun is out, BUT with your back to the sun.
+ If you're not sure, have someone else in your family check. Some people have physically perfect vision, but have a harder time than others distinguishing colors and shades.
+ You can re-do the test, by pouring the pool water + CYA reagent BACK into the little squirt bottle, and then doing it again.

Quote:

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Originally Posted by samtex

My CL seems to be stable overnight but during the day I will loose about 2ppm.

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Losing 2ppm during the day is not unreasonable. With a CYA of under 30, I'm actually surprised it is not a lot more than this. Even with a CYA of 50 (which is about what we suggest for most pools), you are not going to go through the day without losing chlorine. That just doesn't happen.