How to Raise pH in a Hot Tub

By Charles Ng’Ang’A, Bachelor of Applied Science in Biochemistry

Before doing anything to increase the PH of your hot tub, you need to know its capacity. Apart from that, you also need to determine the total alkalinity (TA) and PH level of the water at about 12 inches from the surface using a liquid test kit or test strips. This information will help you to accurately determine how much PH increaser you’ll need to achieve your desired PH range. Total alkalinity influences water PH because it acts as a buffer that holds and controls it. The range of total alkalinity should be between 100 to 150 parts per million (ppm). If it is out of this range, adjust it accordingly first by adding an alkalinity decreaser or increaser depending on whether it is high or low, respectively. Seek advice from a pool professional on the best chemicals to use. Low-quality and counterfeit products will either take too long to work, or they may not work at all. This will increase the cost of balancing the chemistry of your tub unnecessarily.

The optimum PH level should be between 7.2 and 7.8, but the ideal spot is anywhere between 7.4 and 7.6. If it falls below 7.2, it should be corrected. One way of raising it to within optimum range is by using chemical PH increasers. Most of them have sodium carbonate or soda ash as the active ingredient. Find out from the instructional manual of your particular increaser how it should be added and the quantity according to the capacity of your tub. For instance, if you choose baking soda or sodium bicarbonate, you may need to add 1 tablespoon per 100 gallons of water. Add the chemical increaser of your choice over the deepest part of your tub and run the pump for an hour or so to allow the chemical to thoroughly circulate. Then do a chemical re-test between 2 to 6 hours. If you haven’t attained the optimum range, repeat this process until you achieve your desired range.

PH increasers have the effect of altering the total alkalinity depending on their constituent active chemical compounds. It’s crucial to re-test this as well every time you add an increaser. After you have achieved your suitable alkalinity and PH range, you can opt to use a water conditioner system such as Silk Balance. Such a system will help to maintain acidity and alkalinity balance for some time. Factors such as other chemicals you add to your hot tub will influence how long the conditioner system will maintain the total alkalinity and PH within the optimum range. Soda ash can cause a cloudy appearance in the hot tub. You can eliminate this by adding a clarifier to the water and you will restore its clear, transparent look.

Another way of eliminating acidity and increasing alkalinity in your tub is by adding fresh, new water to dilute the high acidity. Fresh water is usually neutral to slightly basic depending on its source. Thus, it will lower acidity and raise alkalinity to a certain degree. Always do a chemical test every time you employ this method to find out if you have achieved the desired PH level.

If balancing alkalinity and acidity proves to be a challenge, you may choose to drain your hot tub and start over with clean, fresh water. Add some line flush the day before draining the tub and let the pump run. Clean the inside of the tub after draining it. This will get rid of anything that can affect chemistry balance after you add clean water.


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