Quote Originally Posted by waterbear
Actually, the recommended FC level for hot tubs is usually in the range of 3-6 ppm.
When I said "If you want your disinfectant (HOCl) to be at 6 ppm (which is WAY too high)" I was referring to the disinfecting chlorine, HOCl, not to total free chlorine, FC. Having 6 ppm of HOCl is, generally speaking, way too high. Having 6 ppm FC in the presence of CYA is not at all too high. I'm glad the recommended FC level for hot tubs is higher since with CYA the disinfecting chlorine would be significantly reduced.

Richard