Tetra phosphate minus reduces the key algae nutrient phosphater phosphate encourages the growth of nuisance algae such as green water and blanket weedr tetra phosphate minus binds phosphates thereby helping to prevent the growth of algae and providing a cost effective solution to a common problemr this product is safe for both plants and fishr 250ml treats 5000 litres 1 100 gallonsr can be used throughout the year for maximum effectivenessr dosage instructionsr shake before user use