Get to the root of underwater plant health with API Root Tabs Freshwater Aquarium Plant Fertilizer. This nourishing fertilizer is made with essential nutrients including carbon, iron and potassium to help your freshwater plants flourish. Root Tabs can be used to help new plants settle in your aquarium, or provide a nutritious boost to your existing underwater garden. Simply add tabs to the gravel bed once per month to promote healthy growth and watch your plants thrive.