# Magnesium Carbonate



## X3NiTH (31 Mar 2018)

Magnesium Carbonate, or more specifically - 

4MgCO₃ · Mg(OH)₂ · 5H₂O  (food grade E504)

I can't get my chemistry Kung-Fu to defeat that Ninja equation. I am trying to express the formula as 1g/25L to show ppm for the magnesium and carbonate and calculating the °GH and °KH (°German). 

As an example 1g CaCO₃ / 25L = Ca 16.02 mg/L, CO₃ 23.98 mg/L, °GH 2.24, °KH 2.24

A bonus would be to work out the pH rise of the Hydroxide. 

Dissolution for the above is using Carbonic acid (pressurised CO₂) in RO/DI.

Any help would be much appreciated.


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## dw1305 (31 Mar 2018)

Hi all,
It is a bit of a strange one, but you just just need to break it down into bits. 

First thing is to work out the RMM and the magnesium content. The equation has to balance which is why you have the 4Mg etc. "_If magnesium chloride (or sulfate) is treated with aqueous sodium carbonate, a precipitate of basic magnesium carbonate—a hydrated complex of magnesium carbonate and magnesium hydroxide—rather than magnesium carbonate itself is formed_:"

I couldn't find exactly where your equation came from (from the container?), so I'll use the equation from <"Wikipedia">: Mg(OH)2·3MgCO3·3H2O(s) + Mg(HCO3)2 . 

You just add together the atoms of the elements: 5 atoms of magnesium,   20 atoms of oxygen,  5 atoms of carbon and 10 atoms of hydrogen and use their RAM to get the RMM.

Mg has a RAM of 24.5, C = 12, oxygen 16 and hydrogen 1, giving you (5*24.5) + (20*16) + (5*12) +(10*1) = 512.5 and (122.5/512.5) ~24% Mg. (If you use  4MgCO₃ · Mg(OH)₂ · 5H₂O you get ~25% magnesium).

From that 1g of E504 contains 0.24g of magnesium. That is 240 milligram and ppm is equivalent to mg L-1. 240/25 is ~10ppm (9.6ppm Mg for the Wikipedia formula).

You can do exactly the same for the carbonate (CO3) to give you the percentage CO3, because dGH is measured on a molar basis ("_1 dGH is equivalent to 0.17832 mmol per litre of elemental calcium and/or magnesium ions_") it is the same value for Ca or Mg. The best explanation of the derivation of the units is still the <"Krib: Water Hardness">.

The rise in pH would depend upon the amount of hydrogen ion donors (acids) in the water, Mg(OH)2 isn't very soluble, and it doesn't disassociates fully (it is a weak base). In RO the pH would rise to ~pH12, but you wouldn't need many H+ ions to neutralise it. 

cheers Darrel


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## X3NiTH (31 Mar 2018)

Thanks Darrel

The equation is exactly how it's expressed on the label, sold as Magnesium Carbonate (Minerals-Water.ltd). I was aware of how it is produced after reading up on it before purchase, it was good to see its exact content listed on the label. Figuring for the Magnesium portion I did get the same ~10ppm (exactly 9.6ppm when calculated with no rounding), I just wasn't sure I had it correct.

So going by the above would it be correct to say that dosing 1g to 25L will result in -

Mg 9.6 mg/L, CO₃ 39.4 mg/L, °GH 2.2 °KH 2.2

The 25L RO I can dose with 2.5ml of a liquid concentrate containing humic acid (Microbe-Lift Bio-CO₂ from Maidenhead Aquatics), hopefully that should be enough to take care of the hydroxide.


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## dw1305 (31 Mar 2018)

Hi all,





X3NiTH said:


> Mg 9.6 mg/L, CO₃ 39.4 mg/L, °GH 2.2 °KH 2.2


That sounds about right.





X3NiTH said:


> The 25L RO I can dose with 2.5ml of a liquid concentrate containing humic acid (Microbe-Lift Bio-CO₂ from Maidenhead Aquatics), hopefully that should be enough to take care of the hydroxide.


I would think so, you could try citric acid if you want a cheaper option.

cheers Darrel


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## X3NiTH (31 Mar 2018)

Excellent thanks!

Good to know that Citric acid can be used instead of the humic acid to save on cost. 

I went with the humic acid because I started dosing it recently as a carbon supplement after reading up on humic and fulvic acids, the bonus being their chelation ability with trace minerals (better for the plants). I already had Shirakura Black Water Fulvo+ and had thought about using that for a supplementary carbon supply but that's way more expensive and harder to source than the Microbe-Lift Bio CO₂ which I can get locally. Comparing the two the Shirakura is a much darker concentrate probably because there's likely fulvic acid in it, no idea if the MA offering has this though. Thinking about it I might dose the Fulvo+ to the 25L (water change water container) instead and continue to use the Microbe-Lift daily in the tank for extra carbon.


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## dw1305 (31 Mar 2018)

Hi all, 





X3NiTH said:


> I went with the humic acid because I started dosing it recently as a carbon supplement


People have tried citric acid as a carbon supplement as well. We have an old thread on it <"Citric acid - source of ....">.

cheers Darrel


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## X3NiTH (31 Mar 2018)

I add citric acid when making up an all in one fert solution to keep it stabilised, I was aware that it can be used as a carbon supplement but not a very good one, likewise with acetic acid. 

From what I've read Humic and fulvic acid is much more stable and better long term for getting traces to the plants and from what I've seen its not causing pH shifts down when dosed. I'm using it more for trace chelation properties than the extra carbon, though that is handy as I can't add more gaseous CO₂ to the tank without kicking of a fight for dominance over the upper water column between the two largest emperor males I have, I tried bumping it up again the other day and the whirling fight display went on for 5 hours until the lights went out and it was too dark to fight, they're currently still not happy with each other's company.

If anyone else reads this, I checked the Maidenhead Aquatics website and they only mention Microbe-Lift Bio CO₂ as having humic acid, no mention of fulvic acid, it's a rebadged product for MA and the parent company website has humic and fulvic acid as ingredients under their own branding. I'll assume it's the same recipe for both products.


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## Hanuman (24 Jul 2019)

I have been trying to find an alternative to Grow Microbe-Lift Plants Fe (basically humic acid) because it's not sold where I am. As stated above by @dw1305 citric acid seems to be a very good chelating agent. Of course humic acid also has its own vertues. The only downside I see about humic acid is that it will tint the water column but will also increase ppm (as far as I have read. Not sure if that is true). I found this paper on <"Organic Acids Chelating Agents">. Check page 35 about citric acid.


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## Hanuman (24 Jul 2019)

Reading through some other threads in the forum I came across this comment made by @ceg4048. Perhaps citric acid is not the best option after all. Still looking!



ceg4048 said:


> Thanks for the elucidation Tom. That's a good point about the chelating effects of the acid. So I guess if there were some issues associated with bioavailability of trace metals then there may be some positive effect of chelation. Even so, that chart shows that citric acid is a lousy chelate anyway. And of course, NO, there is little relevance at all to the TCA cycle.


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## rebel (24 Jul 2019)

@Hanuman Thanks for that link. Very simple to understand with regard to Citric acid. Looks to be a credible source.


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## rebel (24 Jul 2019)

Is it possible to make the fulvic/humics mixes by simply boiling oak leaves?


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## Hanuman (24 Jul 2019)

I suppose it would release some but the point of using humic acid was to chelate the traces while being in the solution prior introduction to the tanks. Not sure if boiling oak leave would release enough humic acid for that purpose or maybe you would need to boil a lot of them to get a good concentrate.


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