Water Chemistry basics and common Pool Chemicals

For many new pool owners, one of the toughest parts of owning a pool is understanding and maintaining proper water chemistry. Water chemistry seems almost like a foreign language at first, but the components of pool water chemistry are easily broken down and simplified.

Water Chemistry basics and common Pool Chemicals

Pool Chlorine

Chlorine is the main sanitizer and oxidizer in most swimming pools today. Chlorine has the job of killing bacteria as well as oxidizing waste products such as skin oils and organic matter. A pool with no chlorine will quickly become overrun with algae, while a pool with too high of chlorine will become uncomfortable on the eyes and skin.

Proper chlorine level: 2-6 ppm

Raised by: Calcium Hypochlorite, Sodium Hypochlorite (Bleach), TriChlor (Chlorine Tablets), DiChlor

Lowered by: Time, Sodium Thiosulfate


pH is a measure of how acidic or basic pool water is. Maintaining proper pH is the most important aspect of pool water chemistry. pH affects every single other factor of water chemistry. Low pH can cause extreme discomfort on eyes and skin, destroy alkalinity, corrode pool equipment, prevent proper oxidation of water, and erode plaster. High pH will prevent chlorine from sanitizing the water, cause scaling, and cause extreme discomfort on eyes and skin.

Proper Range: 7.2-7.8

Raised by: Sodium Carbonate (Soda Ash), Borax

Lowered by: Muriatic Acid, Sodium Bisulfate (Dry Acid)


Alkalinity is essentially the pool water’s ability to maintain a stable pH level. Low alkalinity results in huge swings in pH levels, while high alkalinity results in a constant high pH level that is difficult to bring down into range. Low alkalinity causes the same problems of low pH, and vice versa with high alkalinity.

Proper range: 80-120 ppm

Raised by: Sodium Bicarbonate (Baking Soda)

Lowered by: Muriatic Acid

Calcium Hardness

Calcium Hardness is a measure of the free calcium ions in the water. High calcium hardness levels will cause scaling on the plaster and pool equipment, while low calcium hardness will cause the water to leach calcium from the plaster, resulting in plaster erosion. Calcium hardness varies wildly based on region and the source of pool water, so check to see how hard or soft your tap water is essential to keeping calcium levels under control.

Proper range: 200-400ppm

Raised by: Calcium Chloride

Lowered by: Dilution, Reverse Osmosis

While maintaining proper pool chemistry may seem like a daunting task at first, one will quickly discover the tendencies of their pool water and be able to find patterns and solutions to keep their chemistry under control. Please contact us with any other questions or more in-depth explanations of water chemistry!