Closing is in a few hours and I just discovered that the polyquat I added 10 hours ago decreased FC from 8 to 4 so it is barely above minimum chlorine level for my CYA now. This concerns me because the water temperature has risen to 65 degrees because of warm weather this week and it likely won’t go down lower than that for several more days since more unseasonably warm weather is expected today and this weekend. I always close with polyquat since I have a mesh cover but I have never experienced such a big FC drop like this before and never have used it with water this warm. Should I increase FC back up to shock level (8) or my normal chlorine level (6) before closing or would that decrease the effectiveness of the polyquat if I did this? If the polyquat and warmer weather decreases the FC lower or to zero, how long will the polyquat protect my water from algae?
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