Spa bromine tablets keep water safe at 4-6 mg/l: dose 1-3 x 20g tabs per 1,000 L via a floating dispenser, hold pH 7.2-7.6 and shock weekly. UK guide.
Spa bromine tablets keep hot tub water clean and safe by holding a steady bromine residual of 4–6 mg/l. Load 1–3 × 20g tablets per 1,000 litres into a floating dispenser, keep pH at 7.2–7.6 and total alkalinity at 80–120 ppm, test 2–3 times a week and add a weekly non-chlorine shock – that is the whole routine. The slow-dissolving tablets top themselves up between doses, which is why bromine remains the classic low-effort choice for UK spas.
Bromine has two advantages over chlorine at spa temperatures. It stays effective in hot water up to 40°C, where chlorine burns off quickly, and it keeps working across a wider pH band, so a small pH drift does not leave the water unprotected. It is also milder-smelling and gentler on skin and eyes. 20g bromine tablets dissolve slowly over days, releasing hypobromous acid – the active killing agent – at a steady rate. For a fuller comparison of the two systems, see chlorine vs bromine for UK hot tubs.
Starting from a fresh fill? A bromine starter kit bundles the tablets, shock and test strips to get a new tub up and running. For everything the tablets can and cannot do, our bromine tablets guide goes deeper.
Bromine can only work in balanced water. Hold pH at 7.2–7.6 – below 7.0 the water turns corrosive, above 7.8 bathers get itchy eyes and scale forms – and keep total alkalinity at 80–120 ppm so pH stays put between tests. Correct alkalinity first, then pH, then check the bromine level; the spa water balance essentials guide explains the order and the dosing.
Sweat, body oils and cosmetics build up in spa water where the filter cannot remove them. A weekly dose of non-chlorine shock oxidises that waste away – and in a bromine spa it does double duty, reactivating spent bromide back into working bromine. Shock after heavy bathing sessions too, and you will use fewer tablets overall.
Store tablets in their sealed tub, cool, dry and out of reach of children and pets. Never mix bromine with chlorine or any other chemical in dry form – the reaction is dangerous – and never add tablets directly to the water. Wear gloves when handling, wash hands afterwards, and always follow the label directions.
Hold bromine at 4–6 mg/l. Test 2–3 times a week and adjust the floating dispenser's vents – more open raises the level, more closed lowers it.
Use 1–3 × 20g tablets per 1,000 litres in a floating dispenser. A typical 1,500-litre UK hot tub runs on 2–4 tablets, topped up every one to two weeks as they dissolve.
Yes – weekly. Non-chlorine shock removes the dissolved bather waste the sanitiser cannot, and it regenerates spent bromide back into active bromine, so your tablets last longer.
Not in the same dispenser or the same water without a proper changeover. Never mix the two chemicals in dry form, and switch systems only at a drain and refill – see our guide to switching between chlorine and bromine first.