Most of the commercial pools, including the one with the 42 ppm chlorine reading are indoors and have 0 CYA. Most of the residential pools are outdoors and keep their CYA readings between 30-60 ppm.

Do you have an article showing the correlation of disinfecting/oxidation power of chlorine when related to CYA? I've never found a decent source, except when only comparing ORP levels at different CYA levels.

Brad
www.waterworkspools.com