Algaecide - Definition, Glossary, Details - Oilgae
Algae is the cause of the peculiar 'red tide' phenomenon, in which the ocean appears to be covered in blood. Certain kinds of algae give off toxins that can be hazardous to humans, fish and plants. An algaecide or algicide is a substance used for killing and preventing the growth of algae. It is used for chemical treatment of swimming pools, fish ponds and other 'water features' to remove algae. A commercial algaecide is a quick and easy way to remove algae from your pool or pond. Source
When an algaecide is used in a pool or pond, less chlorine can be used for water purification, resulting in water than is more pleasant to swim in, without the stinging eyes and nose that too much chlorine can cause. Regular use of algaecide also prolongs the life of water filtration systems, as there is less plant material to clog the filters and intakes of the pump - Source