Flourish Phosphorus™ is a safe solution (4500 mg/L phosphate) of potassium phosphate that takes the guess work out of phosphate dosing. Unlike competing products that mix nitrate and phosphate in a fixed ratio, Flourish Phosphorus™ (being nitrate free) allows you to dose phosphorus according to the needs of your plants without the risk of overdosing nitrates. When used as directed Flourish Phosphorus™ will enhance and accelerate the growth of aquatic plants without enhancing algae growth. For maximum benefit use with Flourish Nitrogen™ and Flourish Potassium™.