MAGNESIUM
Recommended magnesium levels between 1300-1400
DIY magnesium mix for your saltwater aquarium
Magnesium
The magnesium portion gives us two options, with Part A being preferred from an aquarium chemistry standpoint. Pick one and follow the same dosing directions regardless of which version you select.
Part A RECOMMENDED VERSION
Dissolve Magnesium Sulfate (3 cups) and magnesium chloride hexahydrate (5 cups) in enough purified freshwater to make 3.78L total volume. There will likely be a precipitate that forms. That precipitate is calcium sulfate (calcium as an impurity in the magnesium chloride and sulfate from the Epsom salts). Dosing this is not an issue.
This solution is dosed to the aquarium much less frequently than the alkalinity and calcium parts. For example each time you finish adding a 3.78L of both alkalinity and calcium of Recipe 1, you will only use around 610 mL of magnesium solution, meaning it will need to be purchased less often.
This solution contains about 47,000 ppm magnesium, 70,000 ppm sulfate and 86,000 ppm chloride.
Part B
Dissolve 8 cups of Magnesium Sulfate in enough RODI water to make 3.78L total volume.
This solution is dosed to the aquarium much less frequently than the alkalinity and calcium parts. For example each time you finish adding a 3.78L of both alkalinity and calcium of Recipe 2, you will only use around 610 mL of magnesium solution.
This solution contains about 47,000 ppm magnesium and 187,000 ppm sulfate.
Purchase Magnesium Sulfate and Magnesium Chloride (Delivery Australia wide)