Basic Pool Chemistry

Pool Water balancing is not such a complicated exercise. It is simply the relationship between different chemical measurements in your pool water. Basic swimming pool water chemistry starts with balancing of seven principal factors.

Basic Water Chemistry

Terms: Definitions:
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).
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.
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. It is most efficient to raise the Free Chlorine level in the evening, since none will be lost to sunlight until the next morning. Free Chlorine normally goes down by itself. If you are in a hurry you can lower Free Chlorine with a chlorine neutralizer (sodium thiosulfate). Proper Range (1.0 – 3.0 ppm).
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).
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).
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).
How to Decrease pH Decreasing pH or Adjusting pH levels in water for: hot tubs, swimming pools and spa pools, which should be maintained at a pH Level between 7.2 to 7.8. Note: Hydrochloric Acid lowers pH Levels and Sodium Bicarbonate raises pH Levels.
Disclaimer: “Basic Pool Water Chemistry Guide” is only meant as a basic guide of terms.

Pool Chemicals