SuperNatural Gro Aqua 2.27 kg Gro Aqua is very rich in calcium and are custom buffered for maximum nutrient uptake in both hydroponic and aeroponic applications. Ethylene Diamine Tetraacetate or EDTA is used to chelate Manganese, Copper, Zinc and Magnesium. DTPA is a special chelating agent for iron that is effective over a wider pH range, particularly alkaline conditions. This is especially important for hydroponic growers. These chelates are large organic structures which form a complex with micronutrients. This complex forms a large chelated ion which reduces the ability of the micronutrient to react with the growing medium, making the micronutrient even more available for plant uptake.