Glossary of Pool Chemicals

ALGAE
Microscopic forms of plant life that grow in the water and can discolor and contaminate it. They are brought into the pool by wind, dust storms, or other organic sources. Some varieties are free floating, and others cling to pool surfaces such as walls, steps, and ledges.

ALGAECIDES
Chemicals that kill algae and prevent new algae growth.

ALKALINE
Solids that dissolve in pool water. Usually calcium or other rock-like matter which tend to raise the water's pH. Sometimes called "hardness".

BACTERIA
Microscopic organisms (germs) that can contaminate your pool and cause illness.

CHELATING AGENTS
Chemicals that combine with dissolved metals to prevent water discoloration.

CHLORAMINES
The combined form of chlorine after impurities have been oxidized. Compounds formed when chlorine combines with perspiration, urine, and skin proteins. This form of chlorine causes eye irritation and foul chlorine-like odors. This is not an effective water disinfectant.

CHLORINE
The most commonly used disinfecting agent for swimming pools because it is easy to use and
highly effective.

CHLORINE DEMAND
The amount of chlorine required to destroy bacteria, algae, chloramines, and other swimming pool contaminants. Foreign contaminants in water (such as dirt, leaves, grass clippings, swimmer's wastes, etc.) use up chlorine. The chlorine demand must be satisfied before a "chlorine residual" is available to disinfect the pool water.

CHLORINE RESIDUAL
The chlorine left in the water after the chlorine demand has been satisfied. Also known as "Free Available Chlorine". This is the true measure of potential chlorine sanitizing and disinfecting power available in the water.

CYANURIC ACID
The chemical component which extends the effectiveness of chlorine by protecting it from evaporation and decay due to the effects of strong sunlight. Also known as "Conditioner" or Stabilizer

D P D
A chemical indicator solution used to measure the Chlorine Residual, or "Free Available Chlorine".

DRY ACID
Sodium Bisulfate; a granular form of acid which is used to lower the pH or total alkalinity in a pool.

FREE CHLORINE
Hypochlorous acid or hypochlorite. This is the active chlorine that kills bacteria and algae and keeps your pool clean and clear.

HARDNESS
The amount of calcium or magnesium dissolved in water. High levels contribute to cloudy water and scale deposits. Low levels can cause water to "attack" or dissolve pool plaster and certain metallic components.

HYPOCHLOROUS ACID
The active form of chlorine in water. This is the material that actually performs the sanitizing and the oxidizing. Also known as Free Chlorine.

MURIATIC ACID
A liquid acid used for lowering pH or total alkalinity.

O T O
Orthotolidine. A chemical indicator solution used to measure the total chlorine residual.

pH
A 14-point scale for measuring the acidity/alkalinity level of water. Readings above 7 are alkaline, and a high pH can cause discomfort to swimmers and scaling (precipitation of solids onto pool surfaces.) Readings below 7 are acidic, and can lead to a burning sensation, and erosion of plaster and metal in the pool. The desired range for pH for normal pool water is between 7.2 and 7.6.

P P M
Parts per million, the standard measure of concentration of chemicals in swimming pool water.
For example, one penny in $10,000.00.

PHENOL RED
The chemical indicator solution which measures pH.

SHOCK TREATMENT
Also known as Super-chlorination. The practice of adding five to ten times the normal daily chlorine dose to destroy algae, or to prevent problems after heavy bather loads, prolonged high temperatures, or severe rains.

STABILIZER
Cyanuric Acid, or Conditioner. Prolongs the effective life of chlorine.

TOTAL ALKALINITY
The mix of bicarbonates, carbonates and hydroxides, etc. in water. The correct balance of TA in the water helps water resist rapid changes in pH. If the TA is too high the pH cannot be adjusted to the desired range. If the TA is too low, the pH will swing rapidly from high to low, and it is very hard to keep within the desired range. In extreme cases, some plaster may be dissolved.