The Importance of Magnesium in Aquaponic Systems

Magnesium is a very important plant nutrient and is up with Potassium when it comes to common plant deficiencies in aquaponic systems.

Magnesium is an important part of enzymes, proteins and the machinery of photosynthesis, and when it’s deficient, it can really impact the productivity of your system.

Magnesium is one of the plant nutrients that interacts with potassium and calcium in “antagonistic” or competitive ways.  To confuse the issue more, magnesium deficiencies can also be difficult to differentiate from deficiencies of these other nutrients!  That’s why it’s important to use a key when you’re first starting to diagnose deficiencies. 

What does a magnesium deficiency look like?

Magnesium deficiency is characterized primarily by interveinal chlorosis (yellowing between leaf veins)  with old growth falling off.  Some plants will show burning along the fringes of the leaves, bronze or brown spots on leaves, and occasionally cupping, but most of the time you’ll just have interveinal chlorosis with old growth falling off the plant.

Treating Magnesium Deficiencies

magnesium in aquaponicsTreating magnesium deficiency requires that you keep potassium and calcium at the correct levels too.  The easiest way to do this is to add all three together.  One way to do this is to use hydrated lime and potassium hydroxide together to raise pH. 

When you add 1 part potassium hydroxide and one part hydrated lime together, you raise the concentrations of potassium, calcium and magnesium together in solution.  As your system matures, you’ll learn that each fish feed has different levels of these nutrients, and different crops consume these nutrients at different rates. 

To correct for these different variables, keep your eyes open for any deficiencies and raise increase the ratio of the nutrient that you believe to be deficient.  

In neutral pH systems, you don’t always want to raise pH.  In these scenarios, we typically recommend weekly doses with soluble kelp concentrate powder to supplement potassium, while adding chelated calcium and magnesium in the form of Epsom salts- which is basically a magnesium sulfate.  In this scenario you must be observant, as any deficiency might creep up and require a modification of the amount that you’re dosing each of these nutrients at each week.  

Check out the video:


More on Magnesium

Magnesium isn’t as much of a concern as potassium but it is still very important, and commonly deficient. 

Use the Bright Agrotech key to diagnose deficiencies and don’t be afraid to ask for more information. 

Good luck and happy growing!

 <<<< Download the key here.