Flourish Potassium™contains 50,000 mg/L of potassium suitable for the natural planted aquarium. Potassium is one of several elements that are vitally important to maintaining a vigorous level of growth in a planted aquarium. Potassium can become depleted in a rapidly growing system or when the source water has a low mineral content. In these cases potassium could become the limiting factor to growth. Use Flourish Potassium™ to prevent potassium depletion (signs of which include yellowing in older leaves) and maintain the highest level of growth.