Chlorine

Used to disinfect a pool.  It works by breaking down the microorganisms in your pool on the cellular level.  There are four different types of chlorine commonly used in pools today: gas, liquid, tablet, and granular.  Gas is still used in older larger pools, but is not recommended, since it is dangerously acidic.  Liquid chlorine is good for large commercial pools; tablets are more stabile and effective for residential pools, and granular chlorine is ideal for vinyl pools, but is expensive. The ideal chlorine level is 3.0 ppm, with an acceptable range of 1.0 – 5.0. 

Is the scale used to measure the relative acidity to alkalinity of something.  The scale ranges from 1 – 14 with 7.0 being neutral, like “pure” water.  A low number is an acid, like lemon juice, which causes corrosion; and a high number is a base, like milk, which causes scale.  The ideal pH level is 7.5, with an acceptable range of 7.2 – 7.8.

Alkalinity

Is the measuring of the pool water’s ability to resist changes in its pH level.  How well can the water balance itself? Sodium bicarbonate is used to increase the levels of Total Alkalinity.  The ideal range is 80 – 120 ppm (125 – 170 ppm for vinyl & fiberglass).

Stabilizers (Cyanuric Acid)

Also called Conditioners.  Used to enhance the effectiveness of chlorine based sanitization systems, by protecting the chlorine from UV rays, which breaks down chlorine’s ability to sanitize the pool water.  The ideal level is 50 ppm.

Calcium Hardness

Is the amount of the alkaline earth metal found in your pool water.  If the water is too “hard”, then it becomes too saturated and will deposit calcium carbonate, a whitish crystallized rough area on any pool surface.  If the water is too “soft”, then it is under-saturated, and will aggressively attempt to pull calcium from any pool surface to create balance.  This can be very corrosive to your pool walls.  The ideal range is 200 – 400 ppm.