Drafted to be CPO for NC community pool. Code in our state:
"Pools that use chlorine as the disinfectant must be stabilized with cyanuric acid except at indoor pools or where it can be shown that cyanuric acid is not necessary to maintain a stable free chlorine residual. The cyanuric acid level shall not exceed 100 parts per million."
It also calls for:
For accidents involving liquid stools increase the free chlorine residual and closure time to reach a CT inactivation value of 15,300 then backwash the pool filter before reopening the pool. CT refers to concentration (C) of free available chlorine in parts per million multiplied by time (T) in minutes.
The 15,300 value comes from CDC research that did not include CYA and its reduction of FC disinfection capacity.
It's not hard to comply with these requirements as they oversimplify to the point of ignoring reality. Reality is that CYA changes everything.
Now I don't really like CYA and I keep it just under 30, so low in fact that I can't actually measure it with my K-2006, whose lowest CYA value is 30 ppm.
But even at these low levels I know it has some effect on disinfection and must surely have an effect on AFR response.
Again, I can comply with the law. My question is more about how to keep people healthy in the presence of the required CYA.
Note that I've read and recommend these two threads already on the forum:
cdc guidelines for disinfection...
Thanks for any guidance!!