| Acid | Dry granular -sodium hydrogen sulphate - substance used to lower the pool's pH (toward a more acidic condition) or to lower total alkalinity levels. Also seen as pH minus. Sometimes referred to as Dry Acid. |
| Air Control | The air control is a valve, usually located on the top side of a spa, which controls the amount of air introduced into the hot tub's jets. The air introduced into the jet will make the water more or less forceful depending upon the amount of ‘turn’ on the valve. |
| Air Lock | Results when air bubbles form in the hot tub’s plumbing, most frequently during draining and refilling. |
| Algae | Algae comes in all shapes, sizes and colours. Green algae is the common variety most people are familiar with. Usually caused by lack of good filtration and/or sanitation it appears as spots on surfaces or as slimy sheets, sometimes covering the entire swimming pool.
Black algae possess strong roots which will push into the plaster or tile grout and the head will appear as black or green/blue spots about the size of your little finger nail. Pink algae is more of a bacterium than algae which can streak across the pool.
Yellow algae (mustard algae) is a wall clinger! Over 20,000 species of algae are known to exist. Maintaining proper sanitiser levels and shock treatments will help to prevent or destroy algae. |
| Algaecide | Algaecides work best as a backup to a routine sanitation program. They also help to kill airborne spores as they blow into the pool. A variety of algae treatment products are available. |
| Alkali | Alkali – Sodium Carbonate which dissolves in water to increase the pH level after testing. |
| Alkalinity | Alkaline refers to the condition where the water's pH is above 7.0 (neutral) on the pH scale. It is the opposite of acidic. Usually measured in parts per million (ppm) of Total Alkalinity. |
| Ammonia | Ammonia is a nitrogen-containing compound which can be introduced into the water by swimmers as organic waste (sweat or urine) or by other means. It mixes with chlorine to form bad-smelling chloramines, which are harmful to health. |
| Anti-foam | A chemical added to spa water to reduce the foam which is often caused by body lotions, face creams and residual soap products on swimwear. |
| Automatic Pool Cleaners | Devices which clean or vacuum debris from the walls and floor of the pool. |
| Available Chlorine | The amount of free chlorine that is available to sanitise or disinfect the water. It is also called Residual Chlorine and Free Available Chlorine. |
