Any pond-owner knows the frustration of watching green, slimy algae overwhelm their once crystal-clear pool. Discoloured scum and dense growth beneath the surface also spells danger to precious aquatic life, and needs tackling as quickly as possible. Used weekly for one month, and then monthly (to maintain clarity), this concentrated, 100% bio-natural formula clears algae fast by depriving it of nutrients; leaving water clear and healthy. Harmless to fish, plants and wildlife. One 500ml bottle treats up to 12,500 litres of pond water.