Hello and CYA @ 240-300

[PoolDoc]

It means -- if it's accurate -- that you have enough CYA in your pool without adding more. One way to check is dose with chlorine in the evening, wait, test, and then retest in the AM. If the chlorine doesn't drop much, then you don't have any unusual chlorine demand. Wait again till the following evening, and test again: if it doesn't drop more than 1/3 - 1/2 during a sunny day . . . you have a fair bit of CYA in the pool.

[aylad]

If it's any help, I am in Northwest Louisiana and my pool gets full sun from sunup to sundown and has a pretty heavy bather load from mid April through beginning of Sept--we also have a very warm, humid climate (today's high is 96 degrees, so far)....I keep my CYA at 80-90, and my chlorine in the 8-12 range. No ill effects on the kids, no faded suits or liners, no skin or eye irritation reported.

Janet

[han78216]

My original testing (240-300ppm) and retest after partial drain (160ppm) was done by mixing 3 cups of tab water and 1 cup of pool water. I then multiplied 4 to the reading.

I'm not sure how my testing of 160 is so far from pool store's 70 reading unless diluting water is messing up the reading or pool store's testing is way off.

[PoolDoc]

The tap water is not the problem -- there's no CYA used in potable water treatment. But, there are a variety of ways for CYA tests to be inaccurate -- it's by far the most subjective of the tests in the K2006, and is a good test ONLY in the sense of being better than 'guess-strips', and in being 'good enough', but only barely!

[han78216]

I tested water with K2006 yesterday and it was clearly over 100.
I guess this tells you can't really trust test results from the pool store.

[aylad]

I guess this tells you can't really trust test results from the pool store.

That's why we push for people to learn to test their own water. Pool store test results are designed to sell chemicals..

[chem geek]

+ Analytical observation: Beginning around 2005 (I'll let him comment on this) Chem_Geek took earlier laboratory research and distilled it into an analytical spread sheet that allows calculation of actual HOCl, and -OCl levels, given DPD chlorine levels, pH and CYA levels. Over the past 8 years, both here and at TroubleFreePools, an increasing body of empirical evidence has validated his analytical conclusion that the EFFECTS of chlorine in water are primarily a function of the HOCl and -OCl components. Stabilized chlorine compounds in the water constitute an effective and instantaneously available chlorine RESERVE, but are not themselves active, until the HOCL levels are reduced, allowing the stabilized chlorine compounds to release their 'reserve'.

I moved into a new house that we rebuilt and added a pool in 2003 and used Trichlor pucks in a floating feeder. After one and a half seasons, so halfway through 2004, I started to get an unexplained higher chlorine demand and had a hard time keeping up with the Trichlor pucks, even putting them into the skimmer to dissolve them more quickly (bad to do, but I didn't know that at the time). The water started to turn dull to cloudy. That's when I started looking around for answers and ran into The PoolForum and PoolSolutions where I read about shocking my pool with chlorinating liquid or bleach to kill the algae, getting a proper test kit, checking my CYA level, etc. After lurking for a while, I joined in November, 2004.

I also started to do research to see if I could figure out the chemistry behind the chlorine / CYA chart. I wrote a horribly complex spreadsheet, initially for the saturation index to match the Taylor watergram, but then added the chlorine/CYA equilibrium equations I eventually found that were definitively determined in 1974. I continued to find more and more evidence in scientific peer-reviewed papers in respected journals that this relationship held for pathogen kill times, oxidation rates, ORP levels, etc. The actual algae inhibition levels were determined by Ben through observation. My only contribution for my version of the chart was to "normalize" the values in the table to make them more consistent with the chemical theory.

[BigDave]

Thank you, Richard and Ben, if you haven't heard it, from me, my children, and everyone who's heard you (or swum in the pools of those who have). Your contributions to the community of swimmers and exposition and dissemination of the facts regarding swimming pool sanitization are laudable.

[JimK]

Thank you, Richard and Ben, if you haven't heard it, from me, my children, and everyone who's heard you (or swum in the pools of those who have). Your contributions to the community of swimmers and exposition and dissemination of the facts regarding swimming pool sanitization are laudable.

+1

[han78216]

pool sweeper re-piping is going on today and we had to drain about half of pool for it.
We will see how much CYA will come down, as soon as refill for CYA solution is delivered. I used all that came with K2006 already.