Chlorine vs bromine in an inflatable hot tub

How each sanitiser works

Chlorine for hot tubs usually comes as granules (often dichlor) or slow dissolving tablets. It reacts quickly with contaminants and is consumed as it works. Used chlorine combines with sweat and other organic matter to form chloramines, which cause the familiar pool smell. Shocking the water breaks these down.

Bromine usually comes as tablets in a floating dispenser. Used bromine forms bromamines, which still sanitise to some extent, and the bromide left in the water can be reactivated by shocking. That makes bromine slower to set up but steadier once a bank of bromide has built up.

Side by side

The table gives general differences and commonly quoted target ranges. Ranges vary between sources, so use the ones on your test kit and chemical labels.

What your manual allows

Inflatable tub makers give their own advice. Some recommend chlorine, some allow either, and some warn against certain tablet types or floaters that can sit against the liner and damage it. Lay-Z-Spa tubs come with a ChemConnect dispenser, which is designed for the maker's own chemicals; check the manual before putting other products in it.

Never mix chlorine and bromine products, and never mix different chemicals in a container. Add each one to the water separately, with the pump running, as the label directs. If you switch from one sanitiser to the other, it is usually simplest to drain, clean and refill first.

Note:Store hot tub chemicals dry, cool, sealed and out of reach of children. Wear gloves and eye protection if the label advises it, and always follow the chemical maker's instructions.

Testing and dosing

Test strips for hot tubs usually read free chlorine or bromine, pH and total alkalinity. Test before each use in busy periods and at least a few times a week otherwise. Keep pH in the range your test kit gives, commonly around 7.2 to 7.6, because both sanitisers work less well when pH drifts high. See how to read test strips and pH and alkalinity for more detail.

Dose from the water volume. Look up your tub's litres in the manual or use our water volume calculator, then follow the dose on the label.

Which suits an inflatable tub?

Many inflatable owners drain and refill every few weeks or months and use the tub at weekends. Chlorine granules suit that pattern: they are quick to raise, easy to test and simple to dose after use. Bromine suits tubs that stay running for long periods and people who notice the chlorine smell, as long as the manual allows it and the dispenser does not sit against the liner.

Whichever you use, clean filters and a regular shock matter as much as the sanitiser. See what chemicals a hot tub needs for the full short list.

See our hot tub shortlist →

Keeping the routine simple

Most problems with either sanitiser come from an irregular routine rather than the product itself. A simple pattern works for most inflatable tubs: test before use, top up sanitiser after use, check pH and alkalinity a few times a week, rinse the filter every few days and shock weekly or after a busy session, all as the labels direct.

Keep the cover on between uses so leaves and rain do not use up the sanitiser, and shower before getting in to cut down on lotions and sweat in the water. If readings keep drifting or the water turns cloudy, a drain, clean and refill is often quicker than chasing the balance. See cloudy water fixes for the checks in order.

Frequently asked questions

Can I use bromine in a Lay-Z-Spa? Check the manual for your model. Bestway gives its own guidance on chemicals and the ChemConnect dispenser.

Can I switch from chlorine to bromine? Yes, but it is simplest to drain, clean and refill before switching. Never mix the two products.

Why does my hot tub smell of chlorine? A strong smell usually means chloramines have built up. Shocking the water, as the label directs, breaks them down.

Is bromine better for hot tubs? It is more stable in hot water, but chlorine is faster and suits tubs that are drained often. Both work when used correctly.