Frequently Asked Questions About Hot Tub Chlorine


Choosing a good sanitizer for your hot tub can be confusing—there are so many options to decide between! If you’re looking at some of the most popular choices, you might find yourself looking at hot tub chlorine. Chlorine is a very popular choice for swimming pools and some new hot tub owners might not know much about its performance in spa water. Good thing we’re here to answer some of the most frequently asked questions about hot tub chlorine!

What do bromine and chlorine have in common?

Good question! Bromine and chlorine come from the same family of sanitizers known as halogens. Halogens work by attacking bacteria and other microorganisms using oxidation, penetrating the cell structure and neutralizing the contaminants. This effective method of sanitation makes them both popular choices for pool and spa sanitation.

Why is chlorine less effective in hot tubs than bromine?

While it’s the number one choice for swimming pools, hot tub chlorine is less effective than bromine because of the high temperatures in spa water. In addition, chlorine doesn’t come in tablet form and doesn’t have a slow release option so it’s harder to maintain than bromine.

What are the different forms of chlorine?

If you do decide to use hot tub chlorine as your primary sanitizer in your spa, you have a few different options available to you. Most popular are sodium dichlor granules. Di-chlor is the best kind of chlorine for use in spas although it’s a little pricier than other options. It is nearly pH neutral and doesn’t need added stabilizer such as cyanuric acid. While most hot tub professional’s opinion is that it’s best used only as a hot tub shock, it’s fairly stable in high temperatures of hot tub water.

It’s best purchased in the fine formulation so that it will dissolve quickly in the water—the large pellets can take too long to disintegrate and may damage the acrylic if they fall to the bottom and stain or scratch the shell. A drawback of dichlor is that you have to test the water more frequently because it’s not available in a time-release tablet or sanitizer cartridges.

How do I add granulated chlorine to my hot tub?

To add granulated chlorine to water, measure and add it to a bucket of water to dissolve and then add to the spa once the granules have liquefied. Never add other spa chemicals to the bucket in which you dissolve the granules—this could result in some nasty gases and/or other unpleasant side effects.

Is salt chlorine an option for hot tubs?

Salt Chlorine is another good choice for sanitizing hot tub water. An alternative device like the Solaxx Saltron Mini Spa Chlorine Generator is easy to install and produces chlorine from mineral salts. It can be installed without having to modify the spa and adapts salt chlorine pool technology for hot tub use.

Are there any kinds of hot tub chlorine to avoid?

Yes! Trichlor tablets are a form of chlorine on the market that are great for pools but NOT recommended for hot tub use. It is highly acidic and dissolves very slowly, becoming problematic when the tablets come in contact with the acrylic shell and bleach or discolor the surface. It may eve cause a permanent ring around the water line in your hot tub.

Another variety that is not recommended for hot tubs is calcium hypochlorite (cal-hypo). It’s popular for pools because it’s relatively inexpensive, but needs to be stabilized with cyanuric acid so that it doesn’t lose its effectiveness in the heat. It has a high concentration of calcium, a high pH, and can leave deposits on parts of the heater, plumbing fittings, and leave a bad ring around the hColor_transition_of_Methyl_red_solution_under_different_acid-base_conditionsot tub shell. Better to spend more money on your sanitizer (dichlor) than to save a little money on chemicals but damage your equipment.

Believe it or not, some people try to sanitize their pool using sodium hypochlorite or household bleach. This product is best left out of your hot tub. It’s very harsh on your water chemistry (pH balance in particular) and has a very aggressive odor.

If I do go with chlorine, what should I keep in mind?

If you choose chlorine over bromine, you’ll need to check your water chemistry more often (2-4 times a week) to be sure your sanitizer levels don’t dip. Otherwise you’re vulnerable to bacteria growth that can lead to itchy skin or red eyes in your bathers.

What chlorine level do I want in my hot tub?

You want your levels to stay between 1.5-30 ppm in a hot tub. You may be costing yourself some time if you choose chlorine as your sanitizer, but when used properly, it can keep your water clean and clear.


If we didn’t answer your question in the post, please post one in the comments! Anything we didn’t cover?
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