Flourish, 4 L / 1 fl. gal. Comprehensive supplement for the planted aquarium Contains a rich assortment of important micro elements, trace elements and other nutrients including calcium, magnesium, and iron These elements have been shown to be beneficial to aquatic plants For macro element fertilization (NPK) use Flourish Nitrogen, Flourish Phosphorus, or Flourish Potassium as needed 250 milliliters treats 100 gallons for 4 to 6 months