No-Phos is a naturally formulated pool water addictive that removes phosphates from pool water. the existence of phosphates in the water can encourage algae growth, as phosphates are nutrients for algae. NO-PHOS is not a Algarecide or algaestat and does not kill algae. Normal sanitizers level will kill algae and NO-PHOS helps with the sanitizer efficiency. Regular use of NO-PHOS will help prevent existence of all types of algae.