DIFFICULTIES IN MAINTAINING
A SAFE CHLORINATED POOL SYSTEM

Chlorine evaporates rapidly:

Chlorine introduced into the water as a gas, liquid or powder is volatile and evaporates from water rapidly, making it almost impossible to keep the required level throughout the water.

The stabilizer is highly toxic:

Cyanuric acid is highly toxic and tends to rise to an unacceptable level if used regularly.

Kill time is unpredictable:

The time it takes for chlorine to contact and kill an unwanted organism is only as short as it should be if a correct and effective free available chlorine concentration level could be maintained.  This is very difficult to do with chlorine, because bacteria and viruses are commonly found growing and rapidly multiplying out of control.  In addition, many species of harmful organisms can build up strong resistance to chlorine, which makes matters worse.

Chlorine in water is corrosive:

 Chlorine is damaging to pool surfaces such as concrete and plaster, as well as pool equipment, tooth enamel and human hair.

Sunlight destroys Chlorine:

It is widely recognized that chlorine is broken down and destroyed by the ultra-violet radiation in ordinary sunlight. This is worse in summer climates.

Warm = Chlorine loss:

Chlorine disappears faster in a warm pool. The warmer the water, the faster it goes. Hence, the perils of hot tubs and spas where if there is too little chlorine you are subject to disease-causing pathogens and if there's enough to kill the pathogens, there's likely enough chlorine to cause health and cosmetic problems.

Uneven evaporation:

Because of rapid evaporation, the water surface (where all the mucous, skin and cosmetic/sun oils accumulate and where bacteria grows rapidly) is not evenly disinfected. Therefore, even chlorine used at very high levels is rarely adequate.