I live in central Alabama, and in the four years I've been here/had my pool, I've never used Polyquat, and I've always opened to crystal clear water. For me, it's a superfluous/unnecesary expense. I just bring it up to shock level one time.

But then, I also don't officially close my pool, just cover and run pump when temps drop below freezing. In the Spring when it starts to warm up, but I don't want to open until first week in May at the very earliest because of all the stuff that rains down from the trees, I will run the pump for several hours a day to keep the chlorine circulated, so maybe that makes a difference, too.