Which hot tub sanitizer should you use? Chlorine or bromine? What about adding a second option, like minerals or salt water? To make this decision and keep your hot tub clear, you need a little knowledge about both sanitizers and how to add them to your hot tub. Watch the video below or keep reading for a quick comparison of bromine vs. chlorine hot tubs.
Chlorine is the most common sanitizer for swimming pools. Bromine is used to sanitize hot tubs and indoor pools more often and with good reason. If your hot tub is indoors, bromine will be the better option.
Simply put, bromine doesn’t have a strong chemical smell like chlorine does. It’s why bromine is preferred over chlorine for indoor pools and hot tubs. However, chlorine is much easier to use and cheaper.
Fun fact: chlorine and bromine are cousins. For you chemical nerds out there, they’re both part of the Halogen family on the periodic table.
Chlorine and bromine are water sanitizers. They kill bacteria and other yucky stuff. But exactly how do these two sanitizers do that?
It oxidizes contaminants by invading them and destroying them from the inside out. The chlorine dissipates and turns into a waste product called chloramines. We refer to these as “dead chlorine” or “used chlorine.” These remnants are responsible for the stinging, drying, stinky reputation chlorine has and reduce the sanitizer’s effectiveness.
To keep chloramines at bay, you’ll need to add chlorine on a regular basis, usually at least once a week. If it gets really bad, though, you can shock your hot tub to get rid of chloramines. You want to do that on a regular basis to keep your water clear and pristine.
It ionizes contaminants, forcing apart their chemical bonds. A good amount of it remains active and working, even after combining with contaminants.
But bromine also produces a waste product called bromamines. While they’re not as noxious as chloramines, they still reduce the effectiveness of the bromine in your hot tub. Shocking is also the solution here.
The measure of a sanitizer’s effectiveness is its reactivity rate. This refers to how quickly it destroys contaminants.
Note: Bromine also has a low pH. It can help keep your overall water chemistry more balanced, which means less adjusting.
Chlorine works fast. But bromine is more stable, especially in warm water and high temperatures.
The exception to this rule is ultraviolet (UV) light from the sun. It’ll destroy bromine faster than chlorine. This is a concern if you have an outdoor hot tub. It makes using your hot tub cover more important.
To get the most from any sanitizer, you need to use enough to work with how much water your hot tub holds. Then, test the water to find the current ppm (parts per million) levels.
If you end up with too much chlorine in your hot tub, you can try a few things to lower the levels. You don’t have to start over with fresh water. The same goes for bromine.
You’ll need to use a larger dose of bromine than chlorine to achieve the same sanitizing results, and bromine costs more than chlorine. But because you don’t have to use it as often, it’s possible that the cost may turn out to be the same. That also depends on the size of your hot tub and how well you keep the water clean and the pH level balanced.
Tests for 7 important chemistries in seconds: Total Hardness, Total Chlorine, Total Bromine, Free Chlorine, pH, Total Alkalinity, and Cyanuric Acid.
The hot tub chemicals you use are all safe in the proper amounts. But some people may react differently to them.
If you or anyone who uses your hot tub on a regular basis has sensitive skin or any kind of upper respiratory difficulties, bromine will likely be the better choice.
These slow-dissolving tablets are compatible with both brominators and floating dispensers, ensuring a steady release and long-lasting defense.
Using a measuring cup, you can add chlorine granules or bromine granules to your hot tub. When you buy these versions, make sure they’re made for hot tubs. Chlorine and Bromine granular’s main active ingredient is sodium dichloro-s-triazinetrione. But we just refer to it as “dichlor.” Bromine granules contain about 10% to 20% sodium bromide.
Easy to add chlorine to your hot tub with granules (powder) and a cap that's perfect for measuring the amounts you add.
You don’t have to add these as often as granules. But the tablet form is still not completely a set-it-and-forget-it method.
40% Thicker Walls, 7-inch Large Chlorine Dispenser For Inground and Above Ground Swimming Pool, 2 Year Warranty (For 3-inch Chlorine Tablets).
The choice between chlorine and bromine tablets and granules should be a lot easier now. But if you still have questions, we did our best to answer them.
Yes. You need to shock chlorine, bromine, and saltwater hot tubs. For all three, you can use the same type of shock. It can be either non-chlorine shock or chlorine shock. Yes, you can use chlorine shock in a bromine hot tub. We recommend avoiding bromine shock altogether. Click here for more information on how to shock a hot tub.
A salt water hot tub is sanitized with chlorine. The salt in the water passes through a generator built into the plumbing system that turns salt into chlorine. The benefit of sanitizing with salt water is that you don’t have to add chlorine manually. The hot tub automatically creates chlorine when it needs it.
Yes. Just make sure you drain and clean your hot tub first. Then, fill it with fresh water before adding in the new preferred sanitizer.
Swim spas are large bodies of water that are normally outside. We recommend using chlorine in a swim spa.
Matt is the founder of Swim University. He's been in the pool industry since 1993. His mission is to make pool care easy for everyone. Each year, he continues to help more people with water chemistry, cleaning, and troubleshooting.
Unsure how much chlorine to add to your hot tub? It only takes a little bit, but it depends on your spa size. Here's a quick guide.
No. Hot tub cyanuric acid (also known as CYA or chlorine stabilizer) is not necessary. It can actually cause more harm than good. Let's learn more.
Do you know how to shock your hot tub? All it takes is knowing what type of hot tub shock to use and when to add it.
