Red Sea Fish Pharm ARE51015 Turbo CO2 Bio Generator Refill Pack Plant Care Products for Aquarium Turbo CO2 bio refill is used to recharge the turbo CO2 bio system The refill is premeasured containing all the components needed to run the bio system for 1 month, just add water Close reactor tightly, place a finger over the open hose connector on the lid and shake reactor gently for 2 minutes