There is a wide range of water treatment chemicals depending on the nature of the problem to be tackled; Algaecides include chemicals such as copper sulphate, rosin amines, iron salts and benzalkonium chloride. They will kill green or blue algae but do not remove their toxins from the water; Antifoams are combinations of oils and silica that break down foaming in an aqueous system. These can be powders or emulsions based on polydimethylsiloxane; Coagulants, generally aluminium and iron sulphates; Corrosion inhibitors react with metallic surfaces and provide protection from any corrosive effects of the water. These can be hydrazine and morpholine or solids such as dicyclohexylamine and cyclohexyamine; Disinfects kill microorganisms in the water. These can be chlorine, chlorine dioxide, ozone and hypochlorite. Chlorine dioxide disinfects surface waters and those with taste and odour problems.
Ozone is a strong though short-live disinfectant that breaks down organisms by oxidising them. Ozone will also purify water by oxidising inorganic contaminants, precipitating them so that they can be filtered out; Flocculants are clarifying agents that cause any suspended particles in the water to aggregate and precipitate away. Otherwise, the water remains cloudy. These are usually soluble polymers based on carboxylates and polyampholytes; pH conditioners are often used in public water supplies to prevent the dissolution of lead from old water pipes. Hydrogen chloride is added to water with a pH higher than 7 while natrium hydroxide is added to acidic water with pH lower than 7.;Resin cleaners regenerate water softening media. Examples are potassium chloride, sodium chloride, chlorine dioxide and citric acid.; Scale can form on surfaces that are in contact with water often as calcium compounds such as calcium carbonate, sulphate and silicate. Scale inhibitors are polymers that attach to these compounds before they precipitate. Phosphoric acid, phosphate esters and polyacrylic acid are some examples.