Fast-acting bromine granules for hot tubs and spas. A BCDMH-based granular sanitiser that establishes a bromine bank, then keeps the water gentle on bather skin and stable through wide pH swings.
Available in 1kg, 2.5kg, 5kg, 10kg, 20kg and 25kg tubs.
3 g per 1000 L raises Total Bromine by 1 ppm. Shock dose new water to a minimum of 20 ppm at start-up; hold 4-6 ppm for everyday use. Expect to top up every 2-4 days depending on bather load.
Bromochlorodimethylhydantoin (BCDMH) granules with at least 60% available halogen. The granules dissolve to release both bromine and a small chlorine activator that recycles spent bromide back to active bromine.
BCDMH dissolves to release hypobromous acid (HOBr), the active sanitiser. As it kills bacteria and oxidises waste, HOBr converts to bromide ion. The chlorine fraction in BCDMH then re-oxidises bromide back into HOBr, sustaining the bromine bank with much less product than chlorine alone.
Bromine remains active in the warm, slightly alkaline conditions where chlorine struggles. Hot tub water held at 38 C burns off chlorine 3-5 times faster than bromine. Bromine is the standard professional choice for spas and high-temperature pools.
4-6 ppm for hot tubs and 2-4 ppm for indoor pools.
Top up every 2-4 days at 3 g per 1000 L per 1 ppm needed; shock dose new water to a minimum of 20 ppm after a drain and refill.
After a shock dose, wait at least 40 minutes, then test with a bromine kit before bathing. For routine top-ups, retest and bathe once Total Bromine reads 4-6 ppm.
Approximately 5-6 months of top-ups for a 1500 L hot tub.
Yes, bromine forms fewer skin-irritant by-products than chlorine and is the standard choice for sensitive bathers.
Granules are for fast top-ups and the start-up shock dose; tablets are for slow daily release. Most users run both together.
Bromochlorodimethylhydantoin (BCDMH) at >= 60% available halogen.
Bromine cycles between active HOBr and spent bromide. The bank is the bromide reserve that the chlorine fraction in BCDMH continually re-oxidises.
Yes. Heavy long-term dosing pushes TDS up; refresh the water when TDS exceeds 1500 ppm.
Raise pH to 7.4 and dose 3 g per 1000 L per 1 ppm needed.
Shock with MPS at 17 g per 1000 L; ventilate for 30 minutes.
Dose pH minus weekly; bromine systems run higher pH than chlorine.
Granules dissolve fast for instant top-ups. Tablets give a slow, steady release. Use both together for stable hot tub care.
Bromine is gentler at hot tub temperatures. Stabilised chlorine is more cost-effective for outdoor pools with heavy UV.
How the three main hot tub sanitiser families compare for everyday use, hot water performance and running cost.
| What matters | Chlorine | Bromine | Chlorine dioxide |
|---|---|---|---|
| Best for | Fast, low-cost everyday sanitising | Hot tubs and spas that want a steadier, milder feel | Deep cleans, biofilm removal and problem water |
| Ideal level | 3 to 5 ppm free chlorine | 4 to 6 ppm total bromine | Used as a clean-up dose, not a daily residual |
| Performance in hot water | Burns off faster at spa temperatures | Stays effective in hot water | Used as a strong clean-up dose, often chosen for biofilm problems |
| pH sensitivity | Works best at pH 7.2 to 7.6 | Effective across a wider pH range | Largely unaffected by pH |
| Odour | Noticeable when chloramines build up | Milder than chlorine | Low odour at normal clean-up doses |
| Typical running cost | Lowest day to day | Slightly dearer than chlorine | More per dose, but only used occasionally |
| ClearSpa products | Stabilised chlorine granules and mini tablets | Bromine tablets 20g and bromine granules | Chlorine dioxide |