Calcium and Magnesium additives are specialized nutrients designed to compensate for deficiencies in most nutrient and fertilizer schedules. Calcium and Magnesium (often referred to as Cal-Mag) is almost always needed when using pure, distilled, or reverse osmosis water. Calcium and Magnesium are the most abundant minerals in tap water however much of it is not chelated enough to be absorbed by plants. The majority of the PPM, or EC reading, you obtain from a measuring device is cal-mag.
Calcium, an essential part of the plant’s cell wall structure, improves the absorption of other nutrients by the roots and their translocation within the plant. It activates a number of plant growth-regulating enzyme systems; helps convert nitrate-nitrogen into forms needed for protein formation; and contributes to improved disease resistance.
Magnesium also helps to activate specific enzyme systems. Enzymes are complex substances that build, modify or break down compounds as part of a plant’s normal metabolism.