Healthy pool water is paramount to maintaining the life of the interior surface, pool equipment and your bathing experience. Properly balanced chemistry saves money on chemical consumption and adds years of life to your pool. Properly balanced water means the the water is neither acidic or alkaline.
When using chlorine products, it is important to know what effect the chlorine base has on the make-up of the water. For example, calcium hypochlorite contains 65% available chlorine and 35% inert ingredients. Every time you 'shock' or 'super-chlorinate' the pool water the pH is increase as calcium hypochlorite is alkaline. Trichloro-s-triazinetrione (tri-chlor) on the other hand is very acidic and will lower the pH of the water.
Both of these chlorine types come in granular and tablet form and should NEVER be mixed. If you have a chlorine tablet feeder, chances are you are using tri-chlor to continually chlorinate the water using the filtration system.
Other chemicals used include
muriatic acid to lowers both pH and total alkalinity
cyanuric acid to help keep the sun from burning off the chlorine in the pool
soda ash to raise pH
baking soda to total alkalinity
various algaecides to help chlorine kill and prevent algae growth
Liquid algaecides also need to be handled with care. Copper based algaecides tend to stain plaster interiors with a bluish green hue and relatively inexpensive algaecides tend to create foam in spas.
A silver based algaecide can be used to treat the tough algae known as black algae. This algaecide will penetrate the center of the algae and must also be used with care as it can stain the pool plaster finish with a greyish hue.
Making your own chlorine uses salt that is introduced into the pool water. A level between 2500 ppm and 3500 ppm is commonly used by most chlorine generator manufacturers. This is approximately 1/3 the salt content of a tear drop and helps the bather experience a silkier, soft feel. When testing for Total Dissolved Solids, be aware that the dissolved solid will primarily be salt and should be taken into account when adjusting the maek-up of the water.