Re: Informed noob using Borax!
CYA is a pH buffer, just are the carbonate system is a pH buffer and just as borates are a pH buffer. However, CYA is NOT an algaecide. What you read in the Powerpoint presentation was a reference to the
Sommerfeld/Adamson study that showed that CYA had minimal effect on reducing chlorine effectiveness against algae -- that is NOT the same as saying that it is an algaecide. However, that study is flawed since they did not maintain chlorine levels and instead used amounts of chlorine that equaled the chlorine demand from the algae samples that were added. Most likely, the nutrient broth for the algae contained ammonia or ammonia-like substances that quickly combined with chlorine to form monochloramine which would be at a level independent of the CYA level (since it does not combine with CYA as chlorine does) to kill off algae.
That presentation also refers to the Pinellas county study that is also flawed, but in more subtle ways that I describe in
this thread. Basically, the study didn't look at hypochlorous acid (HOCl) concentration, only at FC and other water parameters. If they did look HOCl, they would have found that it was at least as good a predictor of bacteriological water quality as FC because bacteria are incredibly easy to kill with very low levels of chlorine. So one cannot conclude from the study anything about CYA. There were 49 pools with no measurable FC yet had no green algae and 25 of these had bacteriologically safe water -- in fact, only 4 of the 486 pools had green algae -- perhaps algaecide was being used in some pools which would throw off study results and wasn't a parameter they looked at!
thepoolpros.com said:
Thats what I thought too until I took a few college level chemistry classes
If you know chemistry, then you should read this scientific paper that definitively determined the chlorine/CYA relationship in 1974 (the introduction is readable even if you don't know chemistry well). Since you are an NSPF CPO instructor, you should also read the
Certified Pool Operator (CPO) training -- What is not taught thread and note its numerous scientific references to published peer-reviewed papers. This isn't just theoretical science either, but has been validated by tens of thousands of pool homeowners, service techs, pool store employees and others at both
The PoolForum and here at TFP. The actual algae inhibition levels based on the chlorine/CYA level were first determined by Ben Powell who created The PoolForum and
PoolSolutions websites.
Richard
