STRONTIUM Strontium is a minor element with an average seawater concentration of 8pp. Strontium, along with calcium, plays a vital role in calcification of coral skeleton growth and plays an important role for all other inhabitants in your reef aquarium. Maintaining sea water levels in your aquarium promotes overall health and vitality. Directions:This product is to be used in conjunction with calibrated testing equipment or ICP-OES to determine depletion. 2 drops (0.1ml) will raise 100L of aquarium water by 0.1 ppm. Ingredients:Concentrated Strontium100,000ppm CAUTIONKeep out of reach of children and pets. Not for human consumption. For marine aquarium use only. StorageKeep out of direct sunlight.Always secure cap on.