Interesting read at PA Dept. of Health


TFP Expert
Platinum Supporter
LifeTime Supporter
May 7, 2007
Silver Spring, MD
My favorite quote "Chorine or bromine kit shall be accurate to within 0.1 ppm", which is kind of extreme but possible. However, they then proceed to recommend a standard DPD chlorine test, which will never come close to meeting that standard.

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
San Rafael, CA USA
They go to extreme with recommending not to use any CYA. They'll tend to have lower CC due to faster oxidation, but at the expense of more nitrogen trichloride which is very volatile and irritating. The immediate rate of disinfection by-product (DBP) production will be higher because of the higher active chlorine level. It would be better to use a small amount of CYA, say 20 ppm, even in indoor pools and have 4 ppm FC and also use supplemental oxidation (UV, ozone, non-chlorine shock, enzymes).

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