Now that is is fall, and the temps are cooling down a bit, I would guess that FC loss would be lower than in the summer, but is it normal to lose very little if any at all? My water is clear, and all other readings are normal, except maybe my calcium which is 120, but I have a vinyl lined pool. I tested the FC 3 days ago, and it was 6.5 (13 drops), and I just tested again, and it was 6. That is only a .5 drop in over 3 days, is this normal?