Moss-killing chemicals are available in a variety of brands, and they control moss on a variety of surfaces, ranging from driveways and sidewalks to roofs and lawns. The chemicals used in a particular brand are determined by the type of surface for which they are intended.
Zinc is one of the active ingredients in moss killers used on roofing. Strips of zinc attached to roof fixtures can kill moss and prevent it from reappearing for up to a year. Zinc is effective when used as a preventive treatment in combination with an initial physical removal of moss.
Zinc sulphate--based moss killers are also effective for use on roofs. They can be applied as a powder or mixed with water to make a sprayable liquid. Chemicals based on zinc sulphate kill moss on rooftops for up to a year. This type of chemical is toxic to aquatic life and is not recommended for use in or near water sources.
A potassium spray uses potassium salts of fatty acids to kill moss. It is non-staining and safe to use on decks, lawns, and roofs. Potassium sprays have little environmental impact but should not be applied directly to water sources.
Iron Chemical Control
Moss-killing chemicals using iron are suitable for use on lawns. Using a fertiliser that contains iron is an effective method for moss control, but it will stain concrete and other surfaces.
Cryptocidal soaps kill moss on contact. Moss-killing soaps tend to bleach moss, but they are safe for use on concrete and other surfaces.