Thanks, Watermom. I actually don't have too much trouble with Cl level usually - maybe b/c there are usually just the boy and me swimming and the pool is mostly shaded all day (never fully sunlit), but I have noticed a real drop after my nephews swim with us. Dirty stinky boys! Aaanyway, I put another pound of CYA into the sock and I'm going to keep the Cl level high for several days just in case. The knowledge on this forum and sister site is well worth the subscriber fee, but what's invaluable is the hand-holding and assurances from you moderators!