BioGuard???ÿBanish???ÿalgicide when used directed, is a highly effective, patented, non-staining algicide that kills and controls algae in swimming pools. It is especially recommended for killing and controlling green, blue-green (frequently called black or spot algae), and mustard algae growths. Banish???ÿalgicide can be used as a remedy for visible algae or to prevent algae from occurring. Banish???ÿis formulated for use in chlorine or bromine sanitized swimming pools of all surface and filter types.