Seachem Flourish Phosphorus helps accelerate and enhance the growth of live aquarium plants, without contributing to nuisance algae growth. This simple, safe solution contains no nitrates, allowing precise phosphorus dosing to meet your plants' needs. Phosphorus supplement for the planted aquariumSafe solution (4,500 mg/L) of potassium phosphateContains no nitrate and does not contribute to algae growthFlourish Phosphorus supplies an ideal concentration (4,500 mg/L) of phosphorus, one of the three macro nutrients required for healthy plant growth (the others are nitrogen and potassium). Unlike competing products, it is nitrate-free and allows you to accurately dose your aquariums phosphate levels without the risk of overdosing nitrates. Use Flourish Phosphorus along with Flourish Nitrogen and Flourish Potassiumto achieve an ideal ratio of all three nutrients. Directions: Beginner: Use 2. 5 mL (half a cap) for each 80 L (20 gallons) once ot twice a week or as needed in response to signs of phosphorus deficiency (such as stunted growth and/or very dark green coloring). 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 a reliable test kit 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. 8x20x0. 1=1. 6 mL. Guaranteed Analysis: Total Phosphate (P2O5) - 0. 3% Soluble Potash (K2O) - 0. 2%