I run my SWG at 100%. If my FC goes up or down when I check it weekly, I adjust the the time the SWG is running. Currently, it runs at 12 hours per day to maintain 6ppm. My CYA is 60-70 ppm.
Is there a scientific way to predict how much time I could reduce the SWG to maintain the FC levels if I raise the CYA to 80 ppm?