It does contain magnesium.
"Aquaforest Reef Mineral Salt is a Sodium Chloride (NaCl) free sea salt. It contains all the other basic components found in natural seawater, such as Magnesium, Calcium, Potassium, Bromine, Fluorine, Barium, Iodine, and trace elements.
NaCl free salt is one of the most important components of the Balling method, and it plays a significant role when Calcium Chloride and Sodium Bicarbonate supplementation is in place." from AF website.
"Aquaforest Reef Mineral Salt is a Sodium Chloride (NaCl) free sea salt. It contains all the other basic components found in natural seawater, such as Magnesium, Calcium, Potassium, Bromine, Fluorine, Barium, Iodine, and trace elements.
NaCl free salt is one of the most important components of the Balling method, and it plays a significant role when Calcium Chloride and Sodium Bicarbonate supplementation is in place." from AF website.


