Algae are microscopic forms of plant life that are introduced into your pool through rain, wind and dust storms. There are many types of algae, some of which are very resistant to regular chemical treatment. For this reason, algae can grow in pools even if the chlorine residual is in the proper range.
It is easier to prevent algae than to kill an existing growth. In algae prone areas (usually, but not limited to, hot humid climates with an abundance of plant life), the use of a good algaecide is recommended on a regular basis.
AQUA NOK-OUT is a highly concentrated algae preventative and algaecide recommended for use in chlorine treated pools. At low dosage levels, usually 250 ml per 10,000 litres every two weeks, AQUA WHAM-O and AQUA SUPER KILL kills algae as it enters your pool, thus preventing it from gaining a foothold and becoming a serious problem. But don't worry if your pool looks like a swamp, a dose of Aqua Wham-o (usually 90 - 150 ml per 10,000 litres) combined with a "shock" treatment can turn your pool into a sparkling blue swimming pool in no time.