Flourish Potassium contains 40;000 mg/L of potassium suitable for the natural freshwater aquarium. Potassium is an important element that is needed by all plants. In a thriving planted aquarium it can become the limiting factor to growth if it is depleted. Flourish Potassium is an integral component of Seachem's plant products and is recommended for use with the entire Flourish line as well as our Flourite gravel. When doing water changes; use Equilibrium to set your initial potassium concentration. Contains no phosphate or nitrate. Flourish Potassium will promote vigorous plant growth while not enhancing algae proliferation. A 500 mL bottle treats 100 gallons for 4-6 months.