Surely you jest?????

I cannot even imagine swimming in anything above 7 or 8 ppm. There are many posts on this forum that relate to burning eyes and other ill effects when swimming at high CL levels.

Many web sites say nothing above 5 ppm and some state regulations close down the community pools if the Cl is above 10ppm.

Swim at 20 ppm?? ---- you can't be serious!!!