Just wanted to update with good news. I did another 4 gallons of 12.5% liquid chlorine the other night and tested one hour later. Finally, I got a high chlorine reading (like 22 ppm). Within an hour of sunrise the next morning, I hadn't lost any FC. That was 3 days ago and I continue to get a chlorine reading so am very excited (today's FC is 3.5 ppm and CC is 0.5 ppm). It seems like I finally broke through and got rid of whatever was keeping me from keeping chlorine in the pool. Altogether, it took over 44 gallons of 12.5% LC this spring but the pool looks great, we're all swimming and life is good. Thanks for all the advice.