Hot tub chemicals: Are you doing it wrong?

hot tub chemical rules

What’s the secret to truly enjoying your backyard hot tub? It’s not an insane number of jets or getting the temperature just right.

Clean, clear water is the key to not only getting the most out of your spa but soaking safely. And the only way to have perfect hot tub water is chemicals. Without chemicals to sanitize the water, your hot tub would become an environment for organisms and algae to grow.

But adding the wrong chemicals and in the wrong order can cause disaster.

With these hot tub chemical rules, you can avoid common mistakes and spend more time soaking in your backyard spa.

clean hot tub
You want the water of your hot tub to be clear, clean, and ready for a relaxing soak. Hot tub chemicals are key to water maintenance.

Hot tub chemical basics

Chemicals are the foundation for maintaining your spa water. But they are not all created equal. As an owner, it’s important to have the necessary products on hand to keep the water clean and clear. 

Ph increaser and pH decreaser

The pH level will tell you how acidic or “basic” your hot tub water is. When your pH is too high, your sanitizer can’t do its job. A low pH can damage the components of your hot tub. Every hot tub owner should have a pH increaser and a pH decreaser readily available.


Sanitizers help get rid of germs and bacteria you don’t want in your hot tub water. Bromine and chlorine are the most popular sanitizers. However, if you own a saltwater hot tub, you will need to refer to your owner’s manual.

Oxidizer or shock

Oxidizer, sometimes called a shocking agent, breaks up bound chlorine and releases oxygen. Using a non-chlorine shock weekly will sanitize the water and remove bacteria, chloramines, and organics in your water.

hot tub chlorine bromine
Chlorine for your hot tub can come in tablets or as granules. Be sure to test your hot tub water before adding chemicals.

Hot tub chemical rules

If you want to keep your spa water clear and clean, you’ll need to keep the chemicals balanced.

But you need to follow these hot tub chemical rules to make sure you avoid major problems like algae and bacteria growth, as well as damage to your spa. 

Water temperature

You want your hot tub water to be, well, hot. For the chemicals to properly disperse, the water should be at least 80 degrees. More than likely, you won’t have to worry about this during routine maintenance. However, it’s an important tip to keep in mind when draining and refilling your hot tub.

Test the water

Before adding any chemicals to your water, you need to know your levels. You can use strips or a liquid test kit to get a chemical reading. Most strips and kits test for pH, alkalinity, calcium hardness, free chlorine and total chlorine. Some will also test for cyanuric acid.

Follow orders

Does it really matter in which order you add hot tub chemicals? Yes, ABSOLUTELY. The alkalinity and pH of your hot tub water need to be in check for a sanitizer to do its job.  To balance your water, start with alkalinity followed by pH. Chlorine can be added next. 

And another helpful tip: Add only one chemical at a time. You can’t balance the water by putting in three products together.

Dry run

Does it seem easier to pre-mix your hot tub chemicals with water? Think again. Hot tub chemicals should be sprinkled evenly over the water. Do not mix them with water before adding them to the spa.

Keep your jets on

The reason you need to keep your jets running is to make sure the chemicals mix well into the water. The jets push water around the spa, moving the chemicals and helping them dissolve and mix evenly.

Wait and retest water 

When you add chemicals to your water, you should wait at least 20 minutes to retest. Add more product as necessary to bring your chemical levels within the proper range.

Keep the cover off

Chemicals need to circulate and off-gas after being added to your water. It is best to leave the hot tub cover off for 15 to 20 minutes. Failing to do so will cause your cover to deteriorate, leaving you with a costly fix. If your hot tub is indoors, be sure to open a window or turn on ventilation to get those chemical vapors out of the room.

Use spa-specific chemicals

Spa chemicals are formulated to work best in hot water and avoid damage to hot tub components. Using other chemicals, even very similar water treatments designed for swimming pools, can cause damage to your spa – or simply not work properly with your water temperature.

Stick to chemicals made specifically for hot tubs, and pay careful attention to usage instructions.

Handle chemicals safely

Hot tub chemicals should be securely stored in a cool, dry place. When adding chemicals to the water, be sure to read and follow all directions on the packaging. Avoid directly touching chemicals and accurately measure quantities.

home spa safety

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