How to measure Magnesium?

[Josh McNeely]

Hi All,

I am a novice in the field of aquaponics. The owners of a local aquaponics were kind enough to allow me to volunteer and learn the ropes. One problem they're having is too much Magnesium, such that it burns the roots.

They asked me to research if there is a way to measure magnesium. Right now, they're using electrical conductivity, but that is just a general measure of nutrient salt concentrations. Is there a recommended water quality kit that tests for Mg?

Thanks,

Josh

[Rob Tolette]

EC would not be a good way to measure magnesium because as you pointed out, that simply measures all salts in the water.

For magnesium you could use a Magnesium Colorimeter like this one.

In our larger farms, I always recommend sending out regular water test for a full agricultural analysis from a lab like MMI.