Skip to main content
    Br

    Bromine

    Bromine is the preferred sanitiser for hot tubs and spas. It stays effective at higher temperatures than chlorine and produces less odour.

    Units: ppm · Last reviewed May 12, 2026

    Why it matters

    Below range, bacteria grow rapidly in warm water. Above range, skin irritation and equipment wear.

    Ideal ranges

    Water typeIdealAcceptable
    Spa / hot tub3 to 5 ppm2 to 6 ppm

    How to test

    1. 1

      Test strips or DPD drop kit

      Bromine reads on the same DPD reagent as chlorine. Multiply chlorine reading by 2.25 if your kit only does chlorine.

    How to correct low bromine

    1. Add bromine tablets to floater or feeder

      Adjust feeder dial to dispense more. Expect 24 hours to reach target.

    2. Shock with non-chlorine shock (MPS)

      Reactivates spent bromide ions back into active bromine.

    How to correct high bromine

    1. Remove tablets, run jets uncovered

      Bromine dissipates with aeration. Drops 1 to 2 ppm per hour with cover off.

    Common causes

    • Heavy use
    • Tablet feeder set too high
    • Insufficient shock between uses

    FAQs

    Can I switch from bromine to chlorine?

    Yes but you must drain and refill. Bromide ions stay in the water and convert any chlorine you add into bromine.

    Related parameters