Reef Advantage Magnesium, 4 kg / 8.8 lbs Raises Magnesium And Contains No Ammonia A Concentrated Optimized Blend Of Magnesium, Chloride, And Sulfate Salts Designed To Restore Depleted Levels Of Magnesium Minimal impact to the ionic ratios found in natural sea water Contains No Ammonia, A Common Contaminant In Every Liquid Magnesium Supplement On The Market 300 Grams Treats 1200 Us Gallons