Premixed Fertilizers

[Unexpected]

Why do so many commercially available liquid fertilizers add Mg to the mix?
Is there not enough from GH alone?

Should I be dosing additional Mg if my Mg is 8ppm from my GH?

 

[Burr740]

Should I be dosing additional Mg if my Mg is 8ppm from my GH?

That should be plenty unless youre rolling with 50+ Ca

 

[Unexpected]

That should be plenty unless youre rolling with 50+ Ca

24ppm Ca

 

[BryceM]

The ratio of Ca/Mg is far more important than the actual quantity, provided that you at least have a little. Somewhere around 3:1 or 4:1 is about right.

Why do they add it? Most likely because it's dirt-cheap and almost never hurts anything.

 

[GreggZ]

In general most tap water dGH is made up of primarily Ca. So my guess is that they add some Mg as the majority of people likely have very little in their source water.