Robert,
we are in South Florida & were having a problem where no CL was being produced, realized our PH was too high and our aquarite swg wasn't producing. Now have ph under control and voila, we have mega chlorine.
We are trying to find a happy medium ...right now its at 70%. We have 10,500 gallons, full sun all day ..... cya about 60-70.

Shari