In case this helps someone else down the line, note that
1 gal of 10% LC added to a 10,000 gal pool equates to 10 ppm increase in FC
1 gal of 10% LC added to a 16,000 gal pool (my size) equates to 6.25 ppm increase in FC
So, if I lose 3 ppm FC per day, I can expect to go through a gallon of...