What does algicide mean?
An algicide is a chemical substance designed to kill or suppress the growth of algae, microscopic or filamentous organisms that thrive in water. Algicides are used wherever uncontrolled algal growth causes problems: swimming pools, ornamental ponds, aquariums, irrigation channels, lakes, and drinking-water reservoirs. Common active ingredients include copper compounds, quaternary ammonium salts, and simazine, each chosen according to the setting and the type of algae targeted. In everyday language the term appears mainly in professional contexts — pool maintenance, water treatment, and aquaculture — rather than casual conversation. A closely related variant spelling, 'algaecide', is equally widespread and refers to exactly the same class of product. Because some algicides can affect non-target organisms if over-applied, careful dosing is important, particularly in natural water bodies where fish and other wildlife may be sensitive to the chemicals involved.
nounA chemical substance used to kill or inhibit the growth of algae, especially in water bodies such as swimming pools, ponds, lakes, and reservoirs.
- A chemical agent that kills or controls algae growth in water systems such as pools, ponds, and reservoirs.
"The maintenance crew added an algicide to the pool to keep the water clear of green algae."
"Before opening the pool for summer, the owner dosed it with a copper-based algicide to prevent any algal bloom."
"Water treatment plants rely on carefully measured algicide applications to keep reservoirs free of nuisance algae."
Standard plural form; used when referring to multiple products or types of algae-killing chemicals.
"Several algicides are approved for use in drinking-water treatment."
The same element that gives pennies their shine — copper — is one of the most widely used ingredients in algicides, poisoning algae while leaving most other aquatic life unharmed.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of algicide
The word 'algicide' is a modern compound formed from 'alga', the Latin word for seaweed or aquatic plant life, combined with the suffix '-cide', from the Latin 'caedere', meaning to kill or cut down. This pattern of coining '-cide' words — as seen in pesticide, fungicide, and herbicide — became productive in the nineteenth and twentieth centuries as chemistry developed agents targeting specific organisms. The term reflects the scientific classification of algae as a distinct group of simple photosynthetic organisms, a field of study known as algology or phycology.
Related word forms
How algicide is actually used
Technical and professional register; encountered mainly in pool maintenance, aquaculture, agriculture, and water-treatment contexts. The variant spelling 'algaecide' is equally common, so both forms should be treated as standard.
Easily confused with algicide
'Algaecide' is a variant spelling of the same word, with 'ae' reflecting the Latin-derived spelling of algae, while 'algicide' uses the simplified modern spelling; both refer to the same substance.