Flourish Potassium, 100 mL / 3.4 fl. oz. Potassium Supplement For The Planted Aquarium A Concentrated Blend 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 Used To Prevent Potassium Depletion, Signs Of Which Include Yellowing Of Older Leaves And To Maintain The Highest Levels Of Growth 250 Milliliters Treats 50 Us Gallons For 4 To 6 Months