Dr. Tank Substrate Fertilizer is a granular all-in-one formula for aquatic plants. It provides both macro and micro nutrients for plants and is combined with natural iron-active laterite to boost root activation. Slow release formula allows plants to uptake the nutrients from the soil over long period of time. HOW TO USE? Sprinkle a even layer covering the bottom of the tank before laying substrate. Supplement with water column and root fertilization based on types of plants in the tank.