The owners manual for my SWCG (Aquarite) states the pool must be balanced before starting the SWCG. I use to use the "superchlorinate" feature (runs at 100%) to shock the pool, but when my first cell died after 4 seasons and I learned how much replacement cells are (ouch!), I decided to only use the SWCG to maintain chlorine levels. Since getting a new cell, I shock with cal hypo and turn the SWCG off when doing so. I expect this will extend the life of the cell.