The FROG Serene Bromine system is an inline sanitizing system for the Caldera Vacanza and Paradise series or Marquis Spas made to keep your water fresher than ever. The green cartridge contains bromine and the blue cartridge contains minerals that work together for optimal sanitization. This self-maintaining system makes taking care of your water effortless, with the bromine cartridge having to be replaced every 2-4 weeks (depending on the size of the spa and how much it's being used) and the mineral cartridge being replaced with every drain, clean, and refill (every 3-4 months).

These are singular FROG Serene Bromine Cartridges with 200 grams of bromine.