# Magnesium deficiency?



## btimmer92 (Mar 12, 2011)

Do plants require magnesium as a nutrient? I do not use it as a gh booster because we have hard water already. But I saw a diagram of plant deficiencies and symptoms, and one of them said magnesium deficiency...


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## VeeSe (Apr 16, 2011)

Yep, plants use magnesium as a trace element.


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## plantbrain (Dec 15, 2003)

btimmer92 said:


> Do plants require magnesium as a nutrient? I do not use it as a gh booster because we have hard water already. But I saw a diagram of plant deficiencies and symptoms, and one of them said magnesium deficiency...


GH is the total Ca and Mg, it does not say if it's all Ca++ or Mg++..........

It's rare it would be 100% Mg.........but it's not rare that there's very little Mg in tap water. Mg is the central atom that makes Chlorophyll green. 

So dosing it extra is generally required and not harmful if it's not needed.


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## Jeff5614 (Dec 29, 2005)

plantbrain said:


> ...Mg is the central atom that makes Chlorophyll green...


So it's not just my imagination. My tank really does look greener since I've been dosing MgSO4.


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## Dempsey (Oct 27, 2009)

You and me both. I just assumed that it was the Fe but I did start dosing extra Fe the same time I started dosing MgSO4.


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## plantbrain (Dec 15, 2003)

http://www.google.com/search?client...&um=1&ie=UTF-8&tbm=isch&source=og&sa=N&tab=wi

Without the Mg, this molecule is a dull grey.

http://intranet.canacad.ac.jp:3445/BiologyIBHL1/3095


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## snausage (Mar 8, 2010)

Ca and Mg are technically secondary macro nutrients, so yes it is important to make sure you have an appropriate amount of both. Ca:Mg ratio is generally thought to be ideal around 4:1.


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## Jeff5614 (Dec 29, 2005)

snausage said:


> Ca and Mg are technically secondary macro nutrients, so yes it is important to make sure you have an appropriate amount of both. Ca:Mg ratio is generally thought to be ideal around 4:1.


And there are others who maintain just the opposite ratio is ideal. Personally I have no idea which is better or the desire to experiment with dosing to find out. I just go with EI and it works for me.


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## plantbrain (Dec 15, 2003)

snausage said:


> Ca and Mg are technically secondary macro nutrients, so yes it is important to make sure you have an appropriate amount of both. Ca:Mg ratio is generally thought to be ideal around 4:1.


This is no factual basis for ratio being of any importance regarding these two elements in aquatic plant plant uptake, nor in terrestrial systems, their ABSOLUTE amounts are important, not the ratio itself. Same with K+ and some of the wonky talk. 

This is what Liebig's Law is about and states. There's nothing to do with ratios regarding that law. Folks might waste a bit more of one nutrients etc, and for a farmer fertilizing 4000 acres, this can = a fair amount of $, but not a hobbyists.

http://www.microsoil.com/liebigs_law_of_the_minimum.htm

I can have 100ppm of Ca and 5 ppm of Mg without any issues, likewise, I can have a Ca of 5ppm and a Mg of 10ppm, again, without any issues.

This is a 40X ratio difference without any impact.
K+, N, P, etc........all behave this way.

You might find some things in terrestrial systems due to concentration being far far more than any aquarist might ever see, where a ratio is so far out of whack, that things causes problems.
But these will be very very far out there.


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## snausage (Mar 8, 2010)

Jeff5614 said:


> And there are others who maintain just the opposite ratio is ideal. Personally I have no idea which is better or the desire to experiment with dosing to find out. I just go with EI and it works for me.


It certainly depends on the plant itself. Those that argue the opposite are probably referring to flowering plants.

If aquarium plants needed lots of Mg and little Ca, it would be a hell of a lot more difficult to grow them in tap water.


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## Hannothan (Dec 26, 2010)

snausage said:


> Ca and Mg are technically secondary macro nutrients, so yes it is important to make sure you have an appropriate amount of both. Ca:Mg ratio is generally thought to be ideal around 4:1.


In terrestrial plants... and even then there's debate as to if there's a proper ratio or if it's a range of ratios. One study I read recently claimed the latter. It's all dependent upon so many variables that finding the perfect ratio for YOUR application is often not worth the added hassle for the marginal gain.

Again, this is for terrestrial plants with more of an agricultural focus. Not aquarium ecology.


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## snausage (Mar 8, 2010)

Hannothan said:


> In terrestrial plants... and even then there's debate as to if there's a proper ratio or if it's a range of ratios. One study I read recently claimed the latter. It's all dependent upon so many variables that finding the perfect ratio for YOUR application is often not worth the added hassle for the marginal gain.
> 
> Again, this is for terrestrial plants with more of an agricultural focus. Not aquarium ecology.


Perhaps you should take a look at the data in this post http://www.plantedtank.net/forums/f...meters/139863-why-mg-deficiency-unlikely.html


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