Dennerle Deponit NutriBalls are the universal nutrient depot for all aquarium plants that take in their nutrients predominantly via their roots. They give new plants a boost to get them started, and older plants a new burst of growing power. Simply push 1-4 balls, depending on the size of the plant, into the area around the roots and replenish every 6 - 12 months. Specifications: - Nutrient depot for all aquarium plants. - Ideal for new plants and for complementary fertilization. - Contains iron and important trace elements. - Boosts growth from the roots up. 30 balls in pack.