Magnesium chloride when not using two part

[jduong916]

I know I’ve read this from Randy before, but I can’t seem to find it. Just wanted to confirm. If I’m using kalkwasser and a calcium reactor, I should use 100% mag chloride (I think the exact ratio was like 7 part mag chloride to 1 part mag sulfate) to supplement magnesium?

 

[Randy Holmes-Farley Verified Community Expert]

I know I’ve read this from Randy before, but I can’t seem to find it. Just wanted to confirm. If I’m using kalkwasser and a calcium reactor, I should use 100% mag chloride (I think the exact ratio was like 7 part mag chloride to 1 part mag sulfate) to supplement magnesium?

Just magnesium chloride is ok, but the optimal recipe is #3 in the article below.


Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

3. A certain mixture of magnesium chloride and magnesium sulfate has no net effect on seawater's major anions (chloride and sulfate). All that is necessary for such a recipe is to add these two ingredients in such a ratio that they add chloride and sulfate in the ratio naturally present in seawater (which is 7.1 to 1 on a weight basis and 9.6 to 1 on a per ion basis).

To perfect such a recipe, it's imperative to know the amounts of sulfate in Epsom salts (39%), the amount of chloride in magnesium chloride hexahydrate (34.9%), and their bulk densities, because most aquarists will use a volume based measurement (1.05 g/cm3 for Epsom salts and 0.85 g/cm3 for magnesium chloride hexahydrate solids). Taking all these factors into account, the desired volume ratio is 10:1, MAG flake to Epsom salts, as a supplement; for instance, 10 cups MAG flake and 1 cup Epsom salts.

 

[jduong916]

Just magnesium chloride is ok, but the optimal recipe is #3 in the article below.


Do-It-Yourself Magnesium Supplements for the Reef Aquarium by Randy Holmes-Farley - Reefkeeping.com

3. A certain mixture of magnesium chloride and magnesium sulfate has no net effect on seawater's major anions (chloride and sulfate). All that is necessary for such a recipe is to add these two ingredients in such a ratio that they add chloride and sulfate in the ratio naturally present in seawater (which is 7.1 to 1 on a weight basis and 9.6 to 1 on a per ion basis).

To perfect such a recipe, it's imperative to know the amounts of sulfate in Epsom salts (39%), the amount of chloride in magnesium chloride hexahydrate (34.9%), and their bulk densities, because most aquarists will use a volume based measurement (1.05 g/cm3 for Epsom salts and 0.85 g/cm3 for magnesium chloride hexahydrate solids). Taking all these factors into account, the desired volume ratio is 10:1, MAG flake to Epsom salts, as a supplement; for instance, 10 cups MAG flake and 1 cup Epsom salts.

And that volume ratio works out to 7.25:0.75 cups of mag flake to epsom salt per gallon. Thanks Randy!