Acidic and alkaline detergents are commonly used for beer tank cleaning.
Acidic detergents include sulfuric acid, nitric acid, phosphoric acid and all organic acids. Hydrochloric acid should not be used for beer tank cleaning because it corrodes the tank and causes it to rust.
Organic acids, such as citric acid, acetic acid and tartaric acid, are less corrosive than nitric acid. Organic acids are minimally corrosive and are an environmentally friendly detergent, but are more expensive.
Alkaline detergents include many inorganic alkaline compounds, such as phosphates, silicates, sodium hydroxide and surfactants. Sodium hydroxide and sodium phosphate are often used for cleaning.
Sodium hydroxide has a good cleaning effect and it is the basis of all detergents with additions ranging from 1.5% to 2%. On the basis of the same concentration, adding a certain amount of surfactant can have better cleaning effect, so adding surfactant can reduce the cost of detergent.
Sodium phosphate is not good for the environment because it contains phosphate.
So usually we choose sodium hydroxide as the lye.