Maintaining correct water chemistry in your pool is essential for health and safety. One of the most common pool chemicals is hydrocholoric acid, often known as muriatic acid. It is a very strong acid used to lower the pH or total alkalinity of the water. It can also be used as an acid washer for cleaning an empty pool.
The pH level of your pool affects every other chemical balance in pool water. pH is a measure of the level of hydrogen ions or acidity of the pool water. Measured on a logarithmic scale, a pH of 0 indicates extremely acidic conditions, and a pH of 14 indicates extremely basic conditions. A pH of 7 is neutral. The most desired pH of pool water is between 7.4 to 7.6, slightly basic. This is the most comfortable range for your eyes and skin, and provides the optimum chlorine levels to prevent bacteria, algae and fungus growth, without developing scale, the white crusty substance often seen on pool tiles, or becoming too corrosive. Hydrochloric acid is often used to adjust pool water back towards this optimum range.
Hydrochloric acid is extremely dangerous. It must be added at the deep end of the pool being careful not to splash the concentrated solution directly onto pool walls or fittings. You should wear rubber gloves and safety glasses when working with hydrochloric acid. Vapors may irritate your respiratory tract. Always add the acid to the water; never add water to the acid.