Very good explanation. Thank you so much. You've been great about answering my question ?The more FC you have in the pool, the more you will lose to the sun.
My recommendation is to test it once daily, preferably in the afternoon. Then figure out what you need to add to get to the top of the range of your CYA per the chart. Add that. Next day, test again, add again. See how much your PPM loss is each day. If it's over 4 then you might want to bump up your CYA by 10 ppm and raise up to the new target value at the top of the new target range. The daily loss should go down with more CYA.
Thanks I've been running 24/7. Because I was slamming and letting filter clean cloudiness out. But now I'm crystal clear I need to back off run time. But I think maybe I should back off slowly until I know what is sufficient. I going to set it for 12 hours first. And go from there. I was just wondering on time of day or night was best? Or it doesn't make any difference?