The pH scale ranges from 0 to 14, with 7 being neutral. Numbers below 7 indicate an acidic state, and numbers above 7 indicate an alkaline state. The ideal range for spa water is 7.4 to 7.6.
ideal range for spa water turer’s instructions, wait the prescribed amount of time, and match the color results on the strip with a colorimeter printed on the canister. Liquid test kits involve taking a water sample, adding a specified amount of reagent, and then comparing the results to a colorimeter. Both types of testing products are available at pool and spa supply stores. For more tips on testing, see 10 Tips for Accurate Water Testing, page 42.
Adjusting pH. Adding an alkali, such as soda ash (sodium carbonate), to the water will cause the pH value to rise. Adding an acid, such as muriatic acid or sodium bisulfate, to the water will cause the pH value to fall. The pH can also be adjusted through the use of specially designed products, typically sold with names like pH Up or pH Down, that are available from swimming pool and spa supply retailers. Add these products, or your selected alkali or acid, following the instructions on the product label. When adjusting pH, keep in mind that most chemicals used in spas even those not designed to adjust pH levels, such as sanitizers and aromatherapy fragrances are acidic or alkaline and therefore will affect the pH level.