Basic Swimming Pool Water Chemistry

Correct water chemistry starts with balancing the following seven principal factors:
Total Alkalinity	Without a proper balance of total alkalinity wild fluctuations in pH may occur. Total alkalinity is raised by adding sodium bicarbonate and lowered by adding sodium bisulfate or muriatic acid.	Proper Range (100 - 150 parts per million or ppm)
pH	When pH is not balanced your bathers experience discomfort and chlorine is rendered useless. It also helps to deteriorate equipment and shorten its life span. Water pH is raised by adding soda ash or caustic soda and lowered by adding sodium bisulfate or muriatic acid.	Proper Range (7.2 - 7.6)
Calcium Hardness	Without a proper balance in calcium hardness calcium is leached from pool surfaces or deposited on equipment. Calcium hardness is raised by adding calcium chloride.	Proper Range (200 - 400 ppm)
Free Available Chlorine	When any chlorine compound is added to the water, the percentage of its strength depends the pH level. At a pH of 7.0, 75% of the chlorine is in the active form of hypochlorous acid. At a pH of 7.5, active hypochlorous drops to 48% and at a pH of 8.0 hypochlorous acid is only 22%.	Proper Range (1.0 - 3.0 ppm)
Combined Available Chlorine	When free active chlorine reacts with ammonia, organic nitrogen compounds and other contaminates in the pool water, chloramines are formed. Chloramines are not an effective disinfectant and are actually the cause of most eye irritation and odor problems. The presence of combined chlorine in water can be removed by the addition of 10 ppm free available chlorine per ppm of combined chlorine or the use of other shocking agents.
Total Dissolved Solids	This is the total amount of all material dissolved in the pool water. As water is reused and chemicals are added, a load develops that adversely affects water balance and efficient operations. The only proper cure is dilution with fresh make-up water.	Proper Range (should not exceed 1,500 ppm)
Temperature	For swimming pools maintained within a range of 75 to 90 degrees Fahrenheit, temperature is not an important factor in proper water balance.