The level of CYA recommended by different manufacturers of SWG varies by manufacturer, but some recommend 70-80 ppm (saying "80 is best"). We don't know for certain why this is. This thread debates this topic but essentially we have two theories and don't know which is true (or which is the predominant factor if both are true):

1) Higher CYA protects chlorine longer and the manufacturers want users to run their SWG cells with less "on" time to maximize cell life and to reduce the rise in pH (from the hydrogen gas bubbles that cause aeration).

2) Higher CYA levels combine with the chlorine that is produced in the SWG cell thereby allowing more to be generated before saturating the cell with disinfecting chlorine. This increases cell efficiency.

Richard