Magnesium supplement for balanced formation of coral skeleton MG Calcium, magnesium, strontium and carbonate are the basic foundation elements of coral skeletons. All of these elements need to be available in balanced proportions for positive coral health and growth. Red Sea’s MAGNESIUM contains blended salts of magnesium and is part of Red Sea’s complete Reef Care Program. Aquarium Type Average daily usage Liquid ml/100L (25gal) Powder g/100L (25gal) Mixed Reef 1ml 0.75g SPS Frag 2ml 1.5g SPS Dominant 2ml 1.5g Ultra Low nutrient SPS 1ml 0.75g Concentration: Liquid supplement: 1ml will raise the Mg level of 100 liters (25 gal) by 1ppm. Powder supplement: 1g will raise the Mg level of 100 liters (25 gal) 1.34ppm. 1 kg will make 1.7L of stock solution. package size/volume : 500 ml (16.9 fl. Oz.)