Read Randy's article and it should clear up any questions.
The "bolding" on preferred method is my doing.
Recipe #2, Part 3: The Magnesium Portion
The magnesium portion again gives us two options,
with Part 3A being preferred from an aquarium chemistry standpoint. Pick one and follow the same dosing directions regardless of which version you select.
Recipe #2, Part 3A
Dissolve Epsom salts (3 cups) and magnesium chloride hexahydrate (5 cups) in enough purified freshwater to make 1 gallon total volume. There will likely be a precipitate that forms even if you fully dissolve both ingredients separately. That precipitate is calcium sulfate (calcium as an impurity in the magnesium chloride and sulfate from the Epsom salts). It is fine and appropriate to dose the precipitate along with the remainder of the fluid by shaking it up before dosing.
This solution is added much less frequently than the other two parts. Each time you finish adding a gallon of both parts of Recipe #2, add 305 mL (1 ¼ cups) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.
The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 47,000 ppm magnesium, 70,000 ppm sulfate and 86,000 ppm chloride.
Recipe #2, Part 3B
Dissolve a 64-ounce container of Epsom salts (about 8 cups) in enough purified fresh water to make 1 gallon total volume. This solution is added much less frequently than the other two parts. Each time you finish adding a gallon of both parts of Recipe #2, add 305 mL (1 ¼ cups) of this stock solution. You can add it all at once or over time as you choose, depending on the aquarium's size and set up. Add it to a high flow area, preferably a sump. In a very small aquarium, or one without a sump, I suggest adding it slowly.
The first time it's added, I recommend adding just a small portion and making sure there isn't any problem (such as corals closing up due to stress) before adding the remainder. Make sure corals and other organisms don't get blasted with locally high concentrations of the main ingredients or impurities, or else they may become stressed. This solution contains about 47,000 ppm magnesium and 187,000 ppm sulfate.
