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Hot Tub Chemical Dosage Chart

One of the major challenges of owning a hot tub is knowing not only which chemicals you need to add to your spa to keep things clean and balanced, but also knowing exactly how much of each chemical is needed. As long as you have a method of testing your water (either test strips or a test kit) and this handy guide, we can help take the guesswork out of hot tub maintenance.
Hot tub test strips

Step 1: Test the water

Using a test strip or a test kit, test your water. Compare the reading to the guide for your test strips or test kit. Using the charts below, compare the results of the test to the charts and using the size of your spa, this chart will help you know exactly which chemical and how much to add to achieve safe and balanced water. 

PH TESTING TIP: To get the most accurate pH test, make sure the jets have been off for at least 2 hours. The jets can artificially increase pH readings.


Ideal ranges for hot tub water balance - sanitizer, ph, alkalinity, calcium hardness

Step 2: Add chemicals as needed to balance the water

Note: Dosage may vary by brand. This is meant to be used as a guide, but always follow the label instructions or recommendations from your spa dealer. 

Total Alkalinity

Adjust alkalinity first. Alkalinity plays a critical role in keeping pH levels stable. Adjust alkalinity first, then pH, and then shock/sanitizers last. If your alkalinity is too low, add the amount of Alkalinity Increaser listed on the chart for your spa size in order to reach the recommended level of 125-150 PPM. 

Hot tub chemical dosage chart alkalinity


Balance the pH levels

Next balance the pH. The ideal pH is between 7.4-7.6. Properly balanced pH will help ensure your sanitizers are working optimally, as well as ensure bather comfort. Out of balance pH can cause burning of the skin or eyes and can also damage your spa equipment. If your test shows the pH is either too high or too low, add the listed amount of either pH Inceaser or pH Decreaser to bring the pH to the proper level. 

Spa maintenance chemical dosage guide pH

Total Calcium Hardness

Once the alkalinity and pH is balanced, calcium hardness is the next to balance for. The recommended range is 100-200 PPM. If the total calcium hardness is below the ideal range, at Calcium Hardness Increaser to bring it to the proper level. If the calcium hardness level is too high, use a Stain & Scale Control product to lower the levels. 

Hot tub chemical dosage recommendations for calcium hardness

Bromine & Chlorine sanitizer

Now it's time to balance the sanitizer levels. Most hot tub owners choose to use either chlorine or bromine as their sanitizer. There are other options such as biguanide, minerals, and others. If you are using a sanitizer other than chlorine or bromine, follow the directions from the manufacturer. 

For chlorine sanitized systems: Ideally you should be keeping the free chlorine level between 3-5 PPM. If you are below that level, add shock and/or chlorine to bring it to the appropriate level. If the chlorine level is too high wait for chlorine levels to go down before using the hot tub or you can add water to dilute. Leaving the cover open with the jets running can help the chlorine dissipate more quickly.

For bromine sanitized systems: The ideal range for free bromine levels is 2-4 PPM if using bromine tablets in a floating bromine dispenser or 3-6 PPM if using granular bromine. To raise the bromine levels add shock and/or bromine until it reaches recommended levels. If the bromine level is too high wait for bromine levels to go down before using the spa or add water to dilute. Leaving the cover open with the jets running can help the bromine dissipate more quickly.

Hot tub sanitizer chemical dosage chart for chlorine and bromine

Spa Chemical Safety

Keep your hot tub chemicals separate from other products. Store them in a cool, dry place that is safely out of reach of children and pets. Never store liquids on top of dry compounds. Keep spa chemicals away from metallic items to prevent possible rusting or deterioration. Keep spa chemicals away from heat or flame. Make sure all products are capped tightly during storage to prevent spilling or contamination. Watch expiration dates on product labels as well as signs of chemical decomposition.

Never mix chemicals of any kind together. An uncontrolled reaction such as fuming, fire or explosion could occur. Always add maintenance products to the spa water separately and in different areas.

Never mix two similar products from different containers together regardless of their similarities. All chemicals are not created the same and may have other chemicals that could react unexpectedly.

When adding chemicals to the hot tub, add them one at a time and in different areas of the hot tub. 

Hot tub chemicals safety guide

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