Watermom, could you ask Ben to look at my last post and see what he thinks of the missing CYA. I've now stopped adding CL, still have the SWG off and am letting the Cl drop. It's come down from 28-18 in 48 hours with only the pump running. Water is still clear. I'm planning on switching back to 8 hrs a day on the pump and starting the swg again tomorrow. I will need to add more CYA again but am confused on where it went. I'm going to test it today and probably put a sock full in the skimmer. The pool is shaded for half the day.