Artificial seawater salt pre-mix (User supplies 9913.9 g NaCl and 2510.5 g USP-grade MgSO4|7(H2O)(Epsom)) with an ionic composition corresponding to Red Sea values at S=40, mixing to a final salinity value of 40.1. Values of major ions and select minor and trace ions (specifically, those which are not considered by researchers to be phytotoxic and which exhibit a nutrient-type depth profile in open oceanic waters) correspond to Red Sea average values (S=40). Clean; no residue in mixing vessels.