Another important component of water quality is pH. pH indicates how acidic or basic the water is. The acceptable range is between 7.2 and 8.0, with ideal levels being around 7.4 or 7.5. The good news is that pH generally stays pretty stable, as long as you have sufficient Alkalinity.
Adding substances that are acidic will lower your pH. Generally, the most common way this happens in a swimming pool is from rain, which is slightly acidic. Low pH (acidic) can contribute to corrosion of pool components and irritate swimmers. If your pH is nearing 7.2 and needs to be raised, you need to add a substance that is a base. The best thing to add is soda ash, which is commonly sold at pool stores as “pH Up”.
High pH means that your water is basic. This condition can irritate swimmers eyes, nose and skin. A rise in pH is most commonly caused in pools by splashing & movement in your pool. Aeration also causes a rise in pH. If your pH is nearing 8.0 and needs to be lowered, then you need to make the water more acidic. The easiest way to do this is to add muriatic acid, which is available at home improvement stores in the paint section. Important Note: pay attention to warning labels and exercise caution in the storage & handling of muriatic acid.
As with other water adjustments, use the calculator at www.poolcalculator.com to determine how much pH Up or muriatic acid to add.