Available across the HotSpot range of hot tubs, the Bromine based sanitising cartridge is designed to sit neatly in the integrated in line-feeder located in the shell of the spa, where it works to continuously sanitise the spa. Rather than measuring out chemicals, you simply replace the cartridge, which usually lasts up to 3 months. The cartridge has a dial that you adjust depending on how often you use your hot tub. The Bromine cartridge reduces the amount of chemicals required and is also kinder to skin, making it easy to use your spa as often as you want.