Algaecide or algicide is a

biocide A biocide is defined in the European legislation as a chemical substance or microorganism intended to destroy, deter, render harmless, or exert a controlling effect on any harmful organism. The US Environmental Protection Agency (EPA) uses a sli ...

used for killing and preventing the growth of

algae Algae ( , ; : alga ) is an informal term for any organisms of a large and diverse group of photosynthesis, photosynthetic organisms that are not plants, and includes species from multiple distinct clades. Such organisms range from unicellular ...

, often defined in a loose sense that, beyond the biological definition, also includes

cyanobacteria Cyanobacteria ( ) are a group of autotrophic gram-negative bacteria that can obtain biological energy via oxygenic photosynthesis. The name "cyanobacteria" () refers to their bluish green (cyan) color, which forms the basis of cyanobacteri ...

("blue-green algae"). An algaecide may be used for controlled bodies of water ( reservoirs, golf ponds,

swimming pools A swimming pool, swimming bath, wading pool, paddling pool, or simply pool, is a structure designed to hold water to enable Human swimming, swimming and associated activities. Pools can be built into the ground (in-ground pools) or built abo ...

), 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. * Copper(II) sulfate remains "the most effective algicidal treatment". A related traditional use is the Bordeaux mixture, used to control fungus on fruits. *

Hydrated lime Calcium hydroxide (traditionally called slaked lime) is an inorganic compound with the chemical formula calcium, Ca(Hydroxide, OH)2. It is a colorless crystal or white powder and is produced when quicklime (calcium oxide) is mixed with water. A ...

, as a biocide, is allowed in the production of organic foods.

Barley straw

Barley Barley (), a member of the grass family, is a major cereal grain grown in temperate climates globally. It was one of the first cultivated grains; it was domesticated in the Fertile Crescent around 9000 BC, giving it nonshattering spikele ...

straw Straw is an agricultural byproduct consisting of the dry wikt:stalk, stalks of cereal plants after the grain and chaff have been removed. It makes up about half of the crop yield, yield by weight of cereal crops such as barley, oats, rice, ry ...

, in

England England is a Countries of the United Kingdom, country that is part of the United Kingdom. It is located on the island of Great Britain, of which it covers about 62%, and List of islands of England, more than 100 smaller adjacent islands. It ...

, 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 The Environmental Protection Agency (EPA) is an independent agency of the United States government tasked with environmental protection matters. President Richard Nixon proposed the establishment of EPA on July 9, 1970; it began operation on De ...

(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 The United States of America (USA), also known as the United States (U.S.) or America, is a country primarily located in North America. It is a federal republic of 50 U.S. state, states and a federal capital district, Washington, D.C. The 48 ...

and England. It is unclear how straw actually works. Peinture algicide et fongicide

Synthetic algicides

Synthetic algicides include: *

Benzalkonium chloride Benzalkonium chloride (BZK, BKC, BAK, BAC), also known as alkyldimethylbenzylammonium chloride (ADBAC) is a type of cationic surfactant. It is an organic salt classified as a quaternary ammonium compound. ADBACs have three main categories of use: ...

– "quat" disinfectant that attacks membranes * Bethoxazin – "new broad spectrum industrial microbicide" in 2012, noted as "Canceled in U.S." in 2022 PubChem-EPA query * Cybutryne – banned since 2023 in ship paint * Dichlone – quinone fungicide/algaecide, not persistent in soil * Dichlorophen – also kills invertebrate animals and bacteria * Diuron – herbicide/algaecide, inhibits photosynthesis * Endothal – herbicide/algaecide, inhibits protein phosphatase 2A * Fentin – quinone fungicide/algaecide, discontinued * Isoproturon – selective substituted urea herbicide, discontinued * Methabenzthiazuron – substituted urea herbicide, discontinued * Nabam – fungicide/algicide discontinued in the EU over cancer * Oxyfluorfen – herbicide, "very toxic to aquatic life with long lasting effects" * Pentachlorophenyl laurate * Quinoclamine – herbicide/algicide, not used in most of the EU * Quinonamid * Simazine – herbicide/algaecide, inhibits

photosynthesis Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...

* Terbutryn * Tiodonium

References

{{reflist

External links

National Pesticide Information Center (NPIC)
Information about pesticide-related topics.