Bromine vs chlorine for a hot tub
For a bromine vs chlorine hot tub decision, chlorine costs less and acts faster. Hot water affects bromine less, and it has a weaker odor. Chlorine works best for inflatable tubs.
Answer three questions to find the right fit for your tub.
- Keep free chlorine at this level
- 3 to 5 ppm
- Keep bromine at this level
- 4 to 6 ppm
- pH range where bromine works
- 7.2 to 8.4
- Ideal choice for inflatable tubs
- Chlorine
Bromine vs chlorine hot tub comparison
Each one kills germs. They vary in cost, how they behave in hot water, and the way you add them.
| Chlorine | Bromine | |
|---|---|---|
| Level to hold | 3 to 5 ppm free chlorine | 4 to 6 ppm |
| pH where it works best | 7.2 to 7.8 | 7.2 to 8.4 |
| Smell | A strong chlorine smell once chloramines build up | Milder, though some people still pick up a smell |
| In hot water | Breaks down faster as the water gets hotter | Much more stable at high heat |
| Cost | Cheaper | Costs more |
| Speed | Dissolves and works fast | Dissolves slowly |
| How you add it | Dichlor granules, stirred into the water | Add sodium bromide when filling, use tablets in a floater, then shock |
| Inflatable tubs | What Lay-Z-Spa and Intex care guides use | You must rebuild the bromide base every time you refill |
Bullfrog Spas provides the speed, cost, and pH ranges. Leslie's says bromine stays far more stable than chlorine when heat is high. Smell details follow the glossary inside the Hot Spring owner's manual.
Bromine levels follow CDC guidelines, which set 4 ppm as the minimum for hot tubs. With heavy use, the American Whirlpool manual requests 4 to 6 ppm.
How the three questions decide
How often you soak, your skin type, and your tub determine if you pick bromine or chlorine for hot tub water.
You use chlorine every time with an inflatable tub. The companies that make it design care steps for it, and the water gets swapped out often.
A hard tub favors bromine if a user hates pool smells or has sensitive skin. Bullfrog says it often feels gentler on skin, but skin varies, so switch if it bothers you. A tub used most days also favors bromine because it lasts longer in hot water.
Chlorine is the simpler choice otherwise. It costs less, works fast, and sells almost everywhere. Maintain the right chlorine level and check pH regularly because chlorine weakens as pH rises.
Bromine requires a bromide bank
Starting with bromine tablets alone takes time. Leslie's says they mix chlorine with bromides, which can take weeks to build up. Draining the tub resets this reserve, known as the bromide bank, to zero.
Therefore, add sodium bromide whenever you fill the tub. The American Whirlpool manual specifies 0.5 oz per 100 gallons, or 14 g per 380 litres. To turn bromide into bromine, shock the water next, and keep tablets inside a floater.
Dropping tablets straight into the tub can mark the shell, so never do it. Read your manual first as well. Owners who run Hot Spring's silver ion purifier are told by Hot Spring to skip bromine entirely.
Inflatable tubs: why use chlorine
The chemicals guide from Lay-Z-Spa relies on chlorine. It uses chlorine granules for shocking and keeps levels at 3 to 5 ppm. The Intex PureSpa manual suggests using a floater for chlorine tablets to reach 2 to 4 ppm, which is slightly lower.
You also replace the water in inflatable tubs every few months. Using bromine means rebuilding the bromide bank each time. Bestway offers a starter kit for bromine, so it is possible. Chlorine just requires less effort. See inflatable hot tub chemicals for more details.
Switching between the two
Make the switch when you change the water, not in the middle of a season. Leslie's points out that chlorine converts bromide back into bromine. A bromine tub keeps making bromine even if you top up with chlorine.
To change sanitizers, flush the lines and drain the tub. Fill it up again, balance the chemistry, and begin using the new product. For bromine, you need sodium bromide, a shock treatment, and then a floater. Buy strips that test it.
Do not combine chlorine and bromine items in any floater, cup, or bucket. Put chemicals in one at a time while the jets are on.
Common questions
For a hot tub, is bromine better than chlorine?
Bromine smells less and stays more stable in hot water, making it good for sensitive skin and busy tubs. Chlorine costs less and works faster, suiting inflatable tubs and light use.
Mixing bromine and chlorine in a hot tub: is it okay?
Do not run two sanitizers side by side. Put chlorine into bromine water and it turns the bromide into bromine, which means the tub remains bromine-based. Drain and refill the water if you want to return to chlorine.
Does chlorine smell more than bromine?
Most of the time, yes. A strong pool smell comes from chloramines formed by used chlorine, yet used bromine has no sharp odor, says Hot Spring. Bullfrog notes that some people still dislike the bromine smell.
Is it possible to put bromine into an inflatable hot tub?
You can, and Bestway has a bromine kit for sale. Most inflatable manufacturers go with chlorine, but bromine means rebuilding the bromide after every refill.
Why is my bromine reading low when the tub is new?
Tablets by themselves need weeks to build enough bromide. Put in sodium bromide at fill time, shock the water, and allow the floater to maintain the level.