Well, I have given up turning down the SWCG percentage and dropped it to zero so that my chlorine will drop into the desired range. Cold weather, shorter days, and no one using the pool is lowering my chlorine demand to almost nada. It's been sitting above 10 all week as I've dropped the percentage over and over again. I'll test tomorrow to see what 24 hours of no chlorine generation does. Expect my usual cries of "SWCG not keeping up!" come March and April, as I try to dial it in the opposite direction.