Hot Tubs, Swim Spas, Service, and Maintenance

How to Lower Hot Tub pH


Hot tubs do require a certain degree of maintenance and keeping the water properly balanced and sanitary is one of the most important routine tasks that an owner needs to stay on top of. When the water in a hot tub becomes unbalanced or too alkaline, the water conditions quickly deteriorate. When the water becomes too alkaline, the pH level increases and you will need an acid chemical that will be capable of lowering both the pH and alkalinity.

To learn more about what steps you need to take to maintain the proper balance of your hot tub water and how to lower the pH level, keep reading below.

Selecting the Proper Chemicals

In order to lower both the pH and alkalinity of your hot tub water, you will need to add acid. Common choices are liquid muriatic acid or dry sodium bisulfate. When the acid is introduced to the water, it increases the hydrogen concentration and lowers the pH. The acid also reacts with the bicarbonate in the water which is what reduces the alkalinity.

Check Your Measurements

When you are trying to balance your water, it is important to remember that the pH drops faster than the alkalinity, so if you correct the alkalinity first, the pH level will slowly adjust. While each chemical brand or type is different, typically you need approximately 1.23 litres of muriatic acid for every 10,000 gallons of hot tub water. This measurement will drop the total alkalinity by 10 ppm.

Mixing the Chemicals

Following the label instructions, you will need to mix the chemicals and a small amount of water together. Place approximately 8 gallons of your hot tub water into a plastic bucket and then pour the pH decreaser into the water in the bucket and let it dissolve. It is very important to note that the water must be placed in the bucket first and the acid second, as adding the acid first may damage the bucket and not properly mix with the water.

Adding to Hot Tub

Make sure that your hot tub is turned on and running. It also should go without saying that no one is in your hot tub when you are adding the chemicals. Add the chemical mixture in the bucket by gradually pouring in with a controlled motion. If the acid is dumped in too quickly, it can damage the sides or bottom of the hot tub.

Let Balance

Let the pump circulate the water between 3 to 6 hours after you add the pH decreaser. The pumps will thoroughly mix all the water in the hot tub with the acid so that both the pH and alkalinity is consistent. After the right amount of time has passed, test the water alkalinity and then test the pH. If the chemical application has been successful, the alkalinity should already be balanced, however, the pH level may take a little bit longer to adjust. If, however, the alkalinity is still too high, repeat the process until both are balanced.