Mills CalMag is a calcium and magnesium supplement that raises EC levels in soft or RO water and helps prevent secondary nutrient deficiencies, promotes growth and vitality and stabilizes EC. Essential for soft water: CalMag is essential if you live in a soft water area – where your plants will suffer from lack of secondary nutrients. Prevent deficiencies: Calcium and magnesium are the most common deficiencies in plants. Because calcium and magnesium are only effectively absorbed with pH > 6.3. Maximized concentration: Mills Calmag is maximized in concentration, you'll be surprised how long it lasts. Use approx. 1 ml per liter of water to increase the EC to the desired level. To prevent calcium and magnesium deficiencies give your plants 1ml per 1 liter of water without other additives with a pH of 6.5, 1x per week.