Utilizing lanthanum chloride, Agent Green acts as an ion exchanger and uses calcium to bind phosphate into insoluble beads. This is important because the phosphate will not dissolve back into the water while waiting to be swept out by filtration. This formula is relied upon by numerous public and private aquariums to keep their systems clear and free of nuisances associated with high phosphate levels. Safe for reef and all fish. Use as directed. Do not overdose.