Brightwell Aquatics Phosphat-E Liquid Phosphate Remover for all Marine Aquaria 500ml / 17oz Begins to eliminate reactive phosphate immediately upon addition to aquarium Safe for all inhabitants of reef and marine fish-only aquaria Each ml eliminates 1 ppm phosphate in 4 US-gallons of water (250 ml treats 1,000 US-gallons) Helps facilitate the removal of phosphate from aquaria during periods when dissolved organic materia May be used on an ongoing basis to help control phosphate in heavily-stocked aquaria