The PoolRx Booster is the same EPA Registered, all natural mineral formulation that is packed inside the PoolRx and PoolRx Extreme units. The Booster is used in conjunction with these units and adds a low residual of chlorine (0.5ppm residential) (1.5-2.0ppm commercial) to effective eliminate all types of algae and bacteria the natural way. Blue Booster minerals need to be added every 4 to 6 months based on bather load, conditions and algae.