Pool Frog Bac PacPool Frog's Bac Pac provides pool owners with a way to supply chlorine to their systems slowly and steadily, enabling maximum chlorine effectiveness. Bac Pac is a cartridge insert that works with all Frog and Cycler systems to provide a way to eliminate constant hand feeding of chlorine on a daily basis to maintain pool health as well as saving considerable time and money with this more efficient, self contained system.