Abstract: A composition comprising a terpene, an emulsifier, and a copper complex is provided, along with methods for its use as an algaecide. The composition is effective when used as an algaecide to treat algae growth in aquatic environments, even though it contains much less terpene than other commonly-used algaecides and can be used without a conventional surfactant. The composition is also less toxic and less flammable than other commonly-used algaecides.

Abstract: A composition comprising a water-dispersible ionene polymer and a water-dispersible di-lower-alkyl ammonium halide polymer (for example, a polymer of dimethyl diallyl ammonium chloride) is disclosed. These polymers are present in the composition in a ratio effective to function synergistically as an algistatic or algicidal agent when an effective amount of the composition is dispersed in a body of water. Examples of suitable bodies of water are swimming pools, spas, lakes, rivers, or water in an industrial water system, such as a cooling water system. Also, a method of treating water which is susceptible to the growth of algae is disclosed. The method is carried out by incorporating in the water an at least algistatic amount of the composition.