If you own a hot tub, keeping it clean and safe for soaking should be a top priority. To achieve this, you need to use the right chemicals. However, knowing which chemicals to use, when to use them, how much to use, and how to add them to your hot tub can be confusing. But don't worry, it's not as complicated as it seems, and once you learn the basics of spa chemicals, taking care of your hot tub will be a breeze.

The Importance of Spa Chemicals

Unlike a bathtub that you fill, use, and immediately drain, the same water stays in your hot tub for weeks or even months. Without proper sanitation, it would quickly become a breeding ground for various organisms that you don't want to soak in. Therefore, using the right spa chemicals is crucial.

Testing your hot tub water is the only way to know which chemicals you need to add and in what amounts. So make sure you have test strips or a liquid test kit on hand at all times, or you can take a water sample to a local pool and spa store and ask them to test it for you.

Common Spa Chemicals

Chlorine is the most common sanitizer and has many advantages, including being cost-effective, easy to add and manage, and an aggressive bacteria and algae killer. It's important to note that if you smell chlorine, it means you don't have enough in your water because it has been used up. Shocking your hot tub can quickly bring the level back up and get rid of chloramines. The proper chlorine level is between 1 ppm and 3 ppm.

Bromine is probably the second-most common sanitizer and has some advantages over chlorine, such as having a lower pH, lasting longer, and being gentler on your skin. However, it also has some drawbacks, such as working more slowly and being unstabilized, which means it'll burn off quickly if used in an uncovered, outdoor hot tub. The proper bromine level is between 3 ppm and 5 ppm.

Minerals such as silver and copper are also used for hot tub sanitation. Mineral sanitizers use one or both of them as active ingredients, allowing you to use less chlorine, making the water less harsh on your skin. However, minerals alone are not enough to sanitize the water properly, so you must supplement them with chlorine to get the full effect. The proper mineral level is between 0.5 ppm and 1.0 ppm.

The Basics of Using Spa Chemicals

Using spa chemicals may seem intimidating, but with a little knowledge, you can take care of your hot tub easily and enjoy soaking in it without worrying about harmful organisms.

  1. Test Your Water Regularly

Testing your hot tub water regularly is essential for maintaining water quality. Use test strips or a liquid test kit to check the levels of chlorine, pH, alkalinity, and calcium hardness. The frequency of testing will depend on the frequency of use and the amount of use.

  1. Adjust Your Water Chemistry

After testing, adjust the water chemistry as necessary to maintain the proper levels of pH, alkalinity, and sanitizer. To raise the pH, add a pH increaser. To lower the pH, add a pH decreaser. To raise alkalinity, add an alkalinity increaser. To lower alkalinity, add an alkalinity decreaser. Use chlorine or bromine to maintain sanitizer levels.

  1. Shock Your Hot Tub

Shock your hot tub after heavy use, when the water has become cloudy or when you detect an odor of chlorine. Shocking the water will destroy bacteria, algae, and other contaminants. Follow the instructions on the shock product for the proper amount and procedure.

  1. Add Sanitizer

Add sanitizer to your hot tub to maintain proper levels of cleanliness.

5. PH 

Another type of spa chemical that can help maintain your hot tub is pH balancers. The pH level of your hot tub water should be between 7.2 and 7.8. If the pH level is too high, you can use pH decreaser, which is usually sodium bisulfate. If the pH level is too low, you can use pH increaser, which is usually sodium carbonate. Balancing the pH level is crucial because it affects the effectiveness of your sanitizer, the comfort of your skin, and the longevity of your hot tub equipment.

6. Alkalinity

Another important spa chemical is alkalinity increaser or decreaser. Total Alkalinity (TA) measures the water's ability to resist changes in pH, so it's an essential factor in maintaining water chemistry. The proper TA level is between 80 and 120 ppm. If the TA is too low, you can use an alkalinity increaser such as sodium bicarbonate. If the TA is too high, you can use an alkalinity decreaser such as muriatic acid.

7. Calcium

Calcium hardness is another factor that can affect the water chemistry of your hot tub. If the water is too soft, it can cause corrosion of metal components, but if it's too hard, it can cause scale buildup. The proper calcium hardness level is between 150 and 400 ppm. You can use a calcium hardness increaser such as calcium chloride if the water is too soft or a sequestering agent if the water is too hard.

8. Clarifiers

In addition to these spa chemicals, you can also use clarifiers and enzymes to maintain your hot tub. Clarifiers help remove tiny particles that make the water cloudy, while enzymes break down organic contaminants such as body oils and lotions. These chemicals can enhance the effectiveness of your sanitizer and keep the water crystal clear and inviting.


It's essential to follow the manufacturer's instructions when using spa chemicals and to store them in a cool, dry place out of reach of children and pets. Wear protective gloves and eyewear when handling chemicals, and never mix different chemicals together.


In conclusion, taking care of your hot tub doesn't have to be a daunting task. By understanding the basics of spa chemicals and testing the water regularly, you can keep the water clean, safe, and comfortable for soaking. Maintaining the proper levels of chlorine or bromine, pH, TA, and calcium hardness can help prevent the growth of harmful organisms, extend the life of your equipment, and provide a relaxing and enjoyable experience. So don't let the fear of spa chemicals discourage you from owning a hot tub. With the right knowledge and care, you can enjoy the benefits of hot tub soaking for years to come.