My friend has a 20,000 gal SWG plaster pool with CYA set at 50 ppm. On the Chlorine/CYA chart the target FC is 5.7 and the yellow mustard minimum is 7.5, his current FC is 8, can he lower and if so to what with reasonable margin of safety? I believe he has yellow algae as he does not always have the time to maintain his pool.
He has suction side pool cleaner that runs while the pool pump is on, how many turns of water would you recommend? As he does not wish to run his pump longer than necessary, he is retired and wants to keep his electricty bill as low as possible.
The reason for asking this is that if I am understanding this correctly a SWG pool can be maintained at lower levels, and he wants to lower them as his manual states 1-3 ppm chlorine will make the cell last longer. I will advise him on your thoughts.
As I maintain mine at a CYA of 30 and a FC of 5-6 it is hard for me to tell him less. One point of interest is only his wife swims in it once a day.