#1 - Welcome to the forum!

#2 - While Janet 'claims' not to know about SWCG's, she's right on in her advice

If the water is colder than usual and there is ~ no chlorine demand, it's easy for a SWCG to 'overproduce'. The solution is to cut the "on" time for the cell and possibly the pump run time.

5% is as low as you can set your unit so, if it's already set there, you need to actually turn the unit off for "a while" (how long depends on your conditions) to enable you to maintain a proper cl level.

Is there any chance you could post your full chemical results, so the experts here could tell you what level of chlorine you'll be wanting to maintain over the winter?