BioGuard Banish Algicide - 1 Quart BioGuard Banish Algicide - 1 Quart (New packaging) Highly effective pool algae destroyer and prevetative Patented non-staining, non-foaming formula Kills and prevents green, mustard and black algae and works in chlorine or bromine swimming pools BioGuard's Strongest, most powerful algaecide.