Algaecide or algicide is a biocide used for killing and preventing the growth of algae, often defined in a loose sense that, beyond the biological definition, also includes cyanobacteria ("blue-green algae"). An algaecide may be used for controlled bodies of water (reservoirs, golf ponds, swimming pools), but may also be used on land for locations such as turfgrass.

Types

Inorganic compounds

Some inorganic compounds are known since antiquity for their algicidal action due to their simplicity.

Barley straw

Barley straw, in England, is placed in mesh bags and floated in fish ponds or water gardens to help reduce algal growth without harming pond plants and animals. Barley straw has not been approved by the United States Environmental Protection Agency (EPA) for use as a pesticide and its effectiveness as an algaecide in ponds has produced mixed results during university testing in the United States and England. It is unclear how straw actually works.

Synthetic algicides

Synthetic algicides include: