Blue Treasure Reef Sea Salt, 6.7kg Bag The Blue Treasure sea salt for coral reef aquarium contains all trace elements that occur in natural seawater from coral reefs, such as calcium (Ca), magnesium (Mg), iodine (I), strontium (Sr), molybdenum (Mo), iron (Fe), rubidium (Rb), manganese (Mn), barium (Ba), selenium (Se), fluoride (F), bromine (Br), lithium (Li), zinc (Zn), aluminum (Al), nickel (Ni), cesium (Cs), Cobalt (Co), Boron (B), Vanadium (V) and water-soluble B1, B12, etc. It does not contain harmful elements and nutritional elements, such as nitrate (NO3), phosphate (PO4) and silicate (Si ), etc..