Phosphorus is one of the main three macro nutrients (nitrogen, phosphorous, potassium: NPK) required by plants and can often become the limiting factor to growth in a flourishing system. Flourish Phosphorus™ is a safe solution (4,500 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™. Flourish Phosphorus™ is safe for invertebrates such as shrimp.
 
Beginner
Use 2.5 mL (half a cap) for each 80 L (20 US gallons) once or twice a week or as needed in response to signs of phosphorus deficiency (e.g. stunted growth, plant dark green).
 
Expert
The beginner dose raises phosphorus by 0.05 mg/L (0.15 mg/L phosphate). The ideal phosphate level will vary, but generally ranges from 0.15–1.0 mg/L. Use MultiTest™ Phosphate to monitor phosphate levels. To target a specific phosphate increase, dose according to the following formula: 0.8vp=m, where v= volume of tank in gallons, p=desired phosphate increase and m=volume of product to use in mL. For example to raise 20 gallons to 0.1 mg/L phosphate you would use: 0.8*20*0.1=1.6 mL.