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Hot Tub Chemicals: How to Properly Use Them

Posted by Watson's on Jun 9, 2023 3:00:00 PM

Clean, fresh water is the most important part of your hot tub. No matter how many seats or massage jets your spa has, it’s impossible to fully enjoy the experience if you’re soaking in murky water. So, in order to maintain the quality and safety of your hot tub, you’ll need to do regular chemical or salt maintenance.

Also see: How to Maintain Your Hot Tub 

This guide will cover the basics of hot tub chemicals and the steps necessary to add the correct chemicals for the best results. 

What chemicals do you need for a hot tub?

Here are the chemicals you'll typically need to keep your hot tub in good condition: 

  • Chlorine - This is the most common sanitizer used in hot tubs and swimming pools. Chlorine kills bacteria and other harmful microorganisms in the water. 

  • Bromine - Bromine is an alternative to chlorine. It’s especially good for people who are sensitive to the smell of chlorine. Bromine also has longer-lasting effects than chlorine but is a bit more expensive. 

  • pH increaser & ph decreaser - pH is the measure of how acidic or alkaline the water is. You will need to adjust the pH levels regularly to keep them between 7.2 and 7.8, which is the ideal range for a hot tub. 

  • Alkalinity increaser & alkalinity decreaser - The total alkalinity (TA) is a measure of the dissolved alkaline substances in the water. The TA acts as a buffer, preventing dramatic changes in pH levels. You will need to maintain TA levels between 80 and 120 ppm. 

  • Calcium hardness increaser - Calcium hardness refers to the amount of dissolved calcium in the water. You need to maintain calcium levels between 150 and 250 ppm to prevent corrosion of the hot tub components.

  • Salt - If you own a saltwater spa, the salt replaces bromine and chlorine making it gentler on sensitive skin. 


How to Add Chemicals to Hot Tub Water

Adding chemicals to a hot tub is easy, but you need to do it correctly to get the maximum benefits. 


Here's how to add chemicals to hot tub water:

  1. Test the water - Before adding any chemicals, use a test kit to check the pH, TA, and sanitizer levels of the water. 

  2. Adjust the pH and TA - If needed, add a pH or TA increaser/decreaser to balance the levels. 

  3. Add sanitizer -  Add the appropriate amount of sanitizer as per the manufacturer's instructions. Be careful not to overdose as it can cause skin irritation. 

  4. Wait and retest - Wait for at least 30 minutes or as directed by the chemical manufacturer. Then, test the water again to ensure the pH, TA, and sanitizer levels are within the ideal range. 

  5. Enjoy your hot tub - Once the levels are balanced, you can safely use your hot tub. 


It is important to remember that you should never mix chemicals directly in the hot tub water as it can cause a dangerous reaction. Always dissolve the chemicals in a bucket of water and pour the solution into the spa or hot tub.


In what order do you add hot tub chemicals?

The order in which you add hot tub chemicals can make a noticeable difference in effectiveness. Here's the correct order you should add your hot tub chemicals: 

  1. Alkalinity increaser/decreaser 

  2. pH increaser/decreaser 

  3. Calcium hardness increaser 

  4. Sanitizer 


It is important to follow this order for maximum effectiveness. If you add the chlorine or bromine too early, it can cause the pH levels to shift, making them less effective.


Do you need to add shock after filling a hot tub?

Yes, you should shock your hot tub after filling it with water. Simply add the recommended amount of oxidizing shock solution to the water to eliminate any bacteria or other impurities that may have entered your hot tub during the filling process, as per the manufacturer's instructions, and wait for it to dissolve. Once it's dissolved, run the filtration system for four hours or as instructed by the manufacturer.


Can you go in a hot tub without chemicals?

Don’t go in a hot tub that hasn’t been treated with the proper chemicals! 

Chemicals are used to keep the water clean and free from harmful bacteria and other impurities. Going in a hot tub without the proper chemicals is not only unsanitary but can also cause skin irritation and other health problems.

If you own a saltwater spa then it won't require bromine and chlorine to keep it clean but you will have to test the water to ensure the salt levels are balanced.


How soon can you use a hot tub after adding chemicals?

You should wait at least 30 minutes after adding chemicals before using your hot tub. This will give the chemicals enough time to dissolve and distribute evenly throughout the water.


How long do hot tub chemicals last?

The lifespan of hot tub chemicals varies based on how often you use them and factors like temperature, sunlight exposure, and filter operation. 

Generally, chlorine or bromine granules can last up to two months before requiring replacement. Test strips and liquid chemicals have a shorter lifespan, typically lasting up to six months. 

It's important to store your hot tub chemicals in a cool, dry place and away from sunlight to help them last the longest. Avoid storing them under the hot tub or in the pump area, as this can affect their potency.

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If you’re looking for hot tub chemicals or have any questions about the hot tub chemical process, Watson’s has everything you need.

When you shop with us, you’ll find an amazing selection and personalized service, along with the guaranteed lowest prices in the USA. We offer all the furniture you need for your outdoor spaces along with tons of pool and spa supplies to make your home stand out. Shop online or stop by your nearest Watson’s location today.

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