Has anyone else had problems with automatic chlorinators causing circulation issues??
Yeah, lots:
+ Hayward inline chlorinators restrict water flow a LOT, but closing the feed valve on the chlorinator wouldn't change that.
+ Depending on how it's been piped, all offline chlorinators can cause problems by feeding air from one side of the pump, to the pump intake. Resultant problems are quite common, and reduced flow could be an effect. If this were the case, closing the feed valve would improve the situation.