Reef aquarium magnesium dosing calculator

Prepare a magnesium stock solution from chloride, sulfate or a balanced blend and calculate the dose for your aquarium.

How this calculator works

Select the same magnesium salt or blend you will actually dissolve. Magnesium corrections can require substantial dry mass, so check the solubility warning and split large adjustments.

Common questions

Why use a magnesium blend?

A chloride and sulfate blend can avoid adding only one accompanying ion during repeated magnesium dosing.

Why is so much salt required?

Magnesium salts contain water and accompanying ions, so only part of their mass is elemental magnesium.