Magnesium / Calcium 3:1 Ratio

[Conrad Noto]

Magnesium / Calcium 3:1 Ratio

I was thought to use and maintain a 3:1 Magnesium / Calcium Ratio, example if you keep Calcium at 450, Magnesium would be kept at 1350. This keeps the Calcium at maximal bio-absorption. If your Calcium is right, but Magnesium is low it decreases the available useable Calcium. This also is supposed to help keep ph stable. Do you use this ratio?

 

[Cory]

Magnesium / Calcium 3:1 Ratio

I was thought to use and maintain a 3:1 Magnesium / Calcium Ratio, example if you keep Calcium at 450, Magnesium would be kept at 1350. This keeps the Calcium at maximal bio-absorption. If your Calcium is right, but Magnesium is low it decreases the available useable Calcium. This also is supposed to help keep ph stable. Do you use this ratio?

I dont target it. But if levels are above normal im happy.

 

[Randy Holmes-Farley Verified Community Expert]

Magnesium / Calcium 3:1 Ratio

I was thought to use and maintain a 3:1 Magnesium / Calcium Ratio, example if you keep Calcium at 450, Magnesium would be kept at 1350. This keeps the Calcium at maximal bio-absorption. If your Calcium is right, but Magnesium is low it decreases the available useable Calcium. This also is supposed to help keep ph stable. Do you use this ratio?

I'm sorry for being curt, but this is a chemistry forum and details matter. That's just untrue. All of it is untrue. My suggestion is that, wherever you read it, do not take chemical advice from them.

There's no reason to use a ratio. Target both calcium and alkalinity at optimal values, regardless of where the other one is.

Neither calcium nor magnesium has any impact on pH. pH is controlled entirely by alkalinity and carbon dioxide levels in the water.

If magnesium is 1300 ppm, calcium at 400 ppm is no more or less bioavailable than calcium at 500 ppm. If magnesium is 1500 ppm, calcium at 400 ppm is no more or less bioavailable than calcium at 400 ppm if magnesium is 1280 ppm.

It just so happens that the normal ratio of the weights of these ion seawater (not the number of ions) is about 1280 ppm and 420 ppm at 35 ppt. That is the little nugget of truth behind the 3:1.