Does local Govt participate in spreading the stabilized chlorine deceit?

[chem geek]

Sorry I misinterpreted what you wrote.

I've been working with several of them (environmental health directors) and they aren't dumb (in fact, they are quite intelligent), but most are misinformed based on traditional industry statements. Some have seen things like ORP levels that seem to track FC/CYA ratios and some have come across this Pool Water Chemistry thread and communicated with me. I really don't think they are doing any intentional withholding of information. For their commercial/public pool environments, they do set limits on CYA levels and enforce regular testing so in practice this does limit the amount of stabilized chlorine that gets used -- many of these large facilities use chlorine gas or large SWG systems. The ones that do use stabilized chlorine do regular water replacement to keep not only CYA lower but to remove general organic contaminants and salt.

It really isn't the place of the public health departments to put out rules of thumb for the residential market. They do note that continued use of stabilized chlorine products can lead to a buildup of CYA. They just never calculated the specific quantities that really show how quickly the buildup can occur (i.e. every 1 ppm FC from Trichlor adds 0.6 ppm to CYA, etc.).

I think that for the residential market, the place that education needs to get fixed are the training courses such as CPO from NSPF and TECH from APSP. I've written to these organizations and continue to push this issue though nothing definitive has happened yet, but I'm a bulldog when it comes to things like this and I won't give up. Also, the education of pool stores, especially large chains like Leslie's, needs to be improved.

Another area that needs to be addressed is how to handle the protozoan cysts. The current Fecal Accident Response for Pool Staff from the CDC indirectly bans CYA entirely since there is no practical way to kill Crypto using chlorine after a diarrhea accident. Actually, with lower CYA levels it is possible, though difficult, since one just needs to raise the FC to approximately 10 ppm FC higher than the CYA level and that results in roughly the equivalent of 10 ppm FC with no CYA. I've been floating the idea around of using chlorine dioxide generated by adding sodium chlorite to a stabilized chlorine pool. I got the idea when I was in REI and saw some water purification tablets that contained sodium chlorite with Dichlor. Chlorine dioxide is at least 10 times more effective than chlorine against protozoan cysts so a level of a few ppm overnight should be all that is needed (and it needs to be overnight since chlorine dioxide breaks down in sunlight). As for ongoing sanitation that can kill Crypto, it looks like UV might be the best bet, though is still limited by the time it takes to do turnovers of water in the pool (it takes 4.6 turnovers to get 99% of the water exposed to the UV, assuming ideal circulation).

Richard


Attached from:
http://www.cdc.gov/healthywater/pdf/...mendations.pdf