Seachem Reef Advantage MagnesiumÃ¢â€Â¢ is a concentrated (80,000 ppm) optimized blend of magnesium, chloride, and sulfate salts designed to restore depleted levels of magnesium with minimal impact to the ionic ratios found in natural sea water. Reef Advantage MagnesiumÃ¢â€Â¢ contains no ammonia! This is a common contaminant in every liquid magnesium supplement on the market. Severely depleted levels of magnesium (below 800 mg/L) can cause depressed pH levels and an inability to maintain proper calcium levels. Magnesium depletion is commonly associated with the use of kalkwasser. 600 g treats 10,000 L (2,500 gallons).