"Fresh Thoughts on Cyanuric Acid"

[laprjns]

I received and email for poolcenter.com today which had a link to an article by Rob Cox, titled "Fresh Thoughts on Cyanuric Acid". The article sites both Richard Falk (ChemGeek) and Ben Powell's work on the Cya /FC relationship. Cox explanation of Chlorine lock seems a little strange to me.
Could this be the start of the industry recognizing the CYA / FC relationship?

 

[tim5055]

Re: "Resh Thoughts on Cyanuric Acid"

It seems like they have fired the first shot to the masses. I like his closing remarks:

Cyanuric Acid is Complicated

No doubt about it, it's a very unique chemical in the way it gives and takes. Introduced to the pool industry in 1956, it's been around a long time, and just now beginning to be somewhat understood.

For sunny outdoor pools, maintain a level of 20-50 ppm of cyanuric acid. Be sure to test the water before adding CYA to the pool, it can be easy to overdose. Also, keep in mind that Trichlor tablets and Dichlor shock are stabilized, meaning that they contain cyanuric acid. After a small initial dose of CYA on a freshly filled pool (2 lbs per 10000 gallons), you may not need to add any additional stabilizer.

Over several years of using stabilized tablets, you may find your CYA level creeping above 50 ppm, unless you get a lot of rain, or lower the water every year for winterizing, which dilutes the concentration of CYA.

The statement "just now beginning to be somewhat understood" is a little off seeing how long TFP has been around and Ben Powell's site going back to 1996. Maybe almost 20 years is "just now" in the pool business.

The problem will be that pool stores will ignore the information because it comes not only from a competitor, but the worst kind = a web pool store!

 

[chem geek]

Re: "Resh Thoughts on Cyanuric Acid"

The article has the following items that are not quite correct:

After further research into the issue, and collaboration with Richard Falk, the chart below was created, known as "Ben's Best Guess CYA Chart".

which is incorrect. Ben came up with his chart all on his own. I came up with my own chart that used the rough algae-inhibition levels implied in Ben's chart but the values in the chart were made consistent with calculated HOCl levels.

However, as Neil Lowry, respected pool chemist points out in his research, CYA buffers pool water to resist downward changes in pH.

It's Bob Lowry, not Neil, and a significant amount of the info in the "Cyanuric Acid: It Controls Your Pool" article Bob wrote came from me (and I reviewed Bob's article before he published it) including how CYA resists changes in HOCl concentration when the pH changes (not just CYA acting as a pH buffer, which it also does).

The most important thing is that this sort of information is getting out into the pool industry.

 

[Wildcat]

Re: "Resh Thoughts on Cyanuric Acid"

Hard to believe it took 40 years, from 1956-1996 for CYA to be understood. You would think that someone would see the cause and effect of continuous use of CYA/Dichlor and then uncontrolled algae. Wasn't there a reliable CYA test or did they just not care? What did pool owners do before CYA? Bleach? Of so, then the old way was the best way!

 

[chem geek]

Well the chlorine/CYA relationship was definitively determined in 1974 when all the equilibrium constants for the chlorinated cyanurates were accurately determined. Even so, it's not so much that the relationship wasn't understood by some chemists, but they were working for chlorinated isocyanurate manufacturers and it was not in their economic interest to disclose this relationship. They sold Trichlor and Dichlor and not only made money doing so, but made more money selling clarifiers, flocculants, algaecides, "shock", etc. that are needed to combat the problems with higher CYA (and not proportionally higher FC) and these products have a much higher profit margin.