# Is Magnesium powder you use in a reef tank the same as magnesium powder we use for planted tanks?



## john6 (27 Mar 2022)

Dumb question time
I have absolute loads of red sea magnesium powder for my reef tank, can i use it for my planted tank or is it totally different?


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## Hufsa (27 Mar 2022)

Its not a dumb question, does the powder say if it is magnesium sulphate or magnesium chloride?


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## john6 (27 Mar 2022)

It just says Magnesium, no sort of ingredient list either, i looked on the Red Sea website at the msds file but it doesnt say anything about what it actually is.


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## Hufsa (27 Mar 2022)

john6 said:


> It just says Magnesium


Hmmm tricky, what consistency is it? Fine powder, crystals, shape?


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## john6 (27 Mar 2022)

Hufsa said:


> Hmmm tricky, what consistency is it? Fine powder, crystals, shape?


Its a really fine, very white powder, Not as powdery as flour but a similar consistency only not as 'clumpy' as flour.


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## Hufsa (27 Mar 2022)

Well heck, im not sure how to proceed then. I'll ping @X3NiTH and @dw1305


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## mort (27 Mar 2022)

I think it's not just one ingredient in there, if I remember correctly. They were very quiet when I asked the rep and they just said a blend of things. Few aquatic companies like to divulge their "secret family recipes".


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## john6 (27 Mar 2022)

mort said:


> I think it's not just one ingredient in there, if I remember correctly. They were very quiet when I asked the rep and they just said a blend of things. Few aquatic companies like to divulge their "secret family recipes".


It looks and feels different to the mag i bought for ferts but i was hoping i could use it as very rarely use it in my reef so just sat there really, makes you wonder what we are acyually putting in our tanks.


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## dw1305 (27 Mar 2022)

Hi all, 


john6 said:


> red sea magnesium powder for my reef tank, can i use it for my planted tank or is it totally different?





john6 said:


> Its a really fine, very white powder, Not as powdery as flour but a similar consistency


I'm going to guess it is mainly magnesium carbonate (MgCO3). If it is it will have a very low solubility, while magnesium sulphate (MgSO4.7H2O) or magnesium chloride (MgCl2) will be fairly soluble. 

cheers Darrel


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## john6 (27 Mar 2022)

dw1305 said:


> Hi all,
> 
> 
> I'm going to guess it is mainly magnesium carbonate (MgCO3). If it is it will have a very low solubility, while magnesium sulphate (MgSO4.7H2O) or magnesium chloride (MgCl2) will be fairly soluble.
> ...


It dissolves quite quickly and easy just by shaking the bottle


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## dw1305 (27 Mar 2022)

Hi all, 


john6 said:


> It dissolves quite quickly and easy just by shaking the bottle


That useful, so either magnesium chloride (MgCl2) or a mix of MgCl2 and MgSO4.7H20. In that case you could use it, although you wouldn't know exactly how much magnesium you had added.

cheers Darrel


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## john6 (27 Mar 2022)

dw1305 said:


> Hi all,
> 
> That useful, so either magnesium chloride (MgCl2) or a mix of MgCl2 and MgSO4.7H20. In that case you could use it, although you wouldn't know exactly how much magnesium you had added.
> 
> cheers Darrel


Thanks, not much point using it if i dont know how much magnesium ive added.


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## dw1305 (27 Mar 2022)

Hi all,


john6 said:


> Thanks, not much point using it if i dont know how much magnesium ive added.


I couldn't find what it contains, but I have managed to find <"dosing instructions">. You could work out what salt(s) it contains from those values

 "_1ml will raise the Mg level of 100 liters (25 gal) by 1ppm. Powder supplement: 1g will raise the Mg level of 100 liters (25 gal) by 1.34ppm_"

cheers Darrel


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## john6 (27 Mar 2022)

dw1305 said:


> Hi all,
> 
> I couldn't find what it contains, but I have managed to find <"dosing instructions">. You could work out what salt(s) it contains from those values
> 
> ...


Thats what i use in my reef tank so is it the same ppm raise for a freshwater? I know there are lots of things you can use in a reef tank but not in a freshwater.


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## dw1305 (27 Mar 2022)

Hi all,


john6 said:


> so is it the same ppm raise for a freshwater?


Yes, it just depends on the percentage of magnesium in a compound.  Both magnesium salts mention are usually <"hydrated">.

"Epsom salts" magnesium sulphate heptahydrate (MgSO4.7H2O) is ~10% Mg and MgCl2.6H2O has a RMM of 203.3, magnesium has a RAM of  24.3, and 24.3/203.3 ~ 8% Magnesium, so it doesn't really matter which compound it is, they both have similar magnesium contents.

If you look at the "Red Sea" details, there is something a little strange.


dw1305 said:


> 1g will raise the Mg level of 100 liters (25 gal) by 1.34ppm


One gram is 1000 milligrams (10^-3) and milligrams per litre are equivalent to ppm (10^-6).  A litre of water weighs 1000 grams,  so 1 g of  magnesium sulphate heptahydrate in 100 litres of water would only give you 1 ppm magnesium and  you would need a less hydrated form of one (or both salts) to get to 1.34 ppm from a 1 gram addition to 100 litres.

cheers Darrel


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## Happi (27 Mar 2022)

john6 said:


> red sea magnesium powder


they say 1 gram in 25 gallon will add 1.34 ppm Mg, this dose matches with MgCl2*6H2O, the exact dose is 1.0607 gram. its not MgSO4*7H2O that they are using because that would have been 1.286 gram. hope this helps


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## dw1305 (27 Mar 2022)

Hi all,





Happi said:


> they say 1 gram in 25 gallon will add 1.34 ppm Mg, this dose matches with MgCl2*6H2O, the exact dose is 1.0607 gram. its not MgSO4*7H2O that they are using because that would have been 1.286 gram. hope this helps


That is the answer. 

It would help if I actually do the simple bit of maths and end up with the right value for 24.3/203.3 .

Cheers Darrel


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## Happi (27 Mar 2022)

I also found this below:

"Red Sea Foundation C is a component of the Red Sea Reef Foundation program for healthy and vibrant corals. Red Sea Foundation C is a blend of magnesium salts in the proper ratio for seawater. Red Sea's dry magnesium additive adds magnesium in proper chloride/sulfate proportions when used with the Red Sea Reef Foundation System."

 they must be adding some part Mgcl and some part MgSo4, I would say very little MgSo4 and lot more MgCl judging by their description of making stock solution. $30 that's way too much

looking at their Foundation program, it seems like they very well could be using both  MgCl2*6H2O and MgSO4*7H2O, for Calcium  its almost always they would use CaCl. but either way their "Foundation System" is nothing but a simple salts which can be easily obtained to make "Several Foundation System" 

*Red Sea Reef Foundation System:

Package Contains:*

250mL Reef Foundation A (Ca,Sr)

250mL Reef Foundation B (Alk)

250mL Reef Foundation C (Mg)

*Reef Foundation A:* 1 mL will raise the Calcium level of 25 gallons by 2 ppm.

*Reef Foundation B:* 1 mL will raise the alkalinity of 25 gallons by 0.036 meq/l (0.1dKH).

*Reef Foundation C:* 1 mL will raise the Magnesium level of 25 gallons by 1 ppm.


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## Zeus. (28 Mar 2022)

Happi said:


> they say 1 gram in 25 gallon will add 1.34 ppm Mg, this dose matches with MgCl2*6H2O, the exact dose is 1.0607 gram. its not MgSO4*7H2O that they are using because that would have been 1.286 gram.










Best check your maths 

I also used 'what if analysis' 'goal seek' in excel and no mix of MgCl2.6H2O and MgSO4.7H2O will give 1.34 ppm Mg in 1.0gram mass. Which is obvious from the pics above ( did the  'what if analysis' 'goal seek' first) 

They must be using some anhydrous MgCL2 which would help hot the 1.34 ppm Mg for 1.0gram in 100 litres  or it could be just some Magnesium Chloride Flakes in their mix from the read sea



Not sure how hydrophilic/stable anhydrous MgCL2 for storing is 😬 am sure @X3NiTH could enlighten us 
But we don't need to hit the magic 1.0gram to match the product as if using   MgCl2.6H2O  (which I am sure is more stable for storing) as all we are adding is a little extra H2O in mass when using  MgCl2.6H2O 
We don't have  anhydrous MgCL2 added to the IFC calculator. But if your keen to find the answer I could add it to my version and find the Cl :SO4 ratio then use that and 'what if analysis' to get the masses of MgCl2.6H2O and MgSO4.7H2O to yield of clone to get 1.34 ppm Mg per 100 litres yielding the same Cl :SO4 ratio

second thoughts they could also be using anhydrous magnesium sulphate -which is a desiccant - we have that on the IFC



So without the [Cl] and [SO4] of the product for 1.0 gram per 100litres we cant do an exact clone as it could be a mix of all four salts


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## Happi (28 Mar 2022)

Zeus. said:


> Best check your maths


I did, MgCl2*6H2O and MgSO4*7H2O grams and ppm are even matching with Rotala calculator. what did I miss????


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## john6 (27 Mar 2022)

Dumb question time
I have absolute loads of red sea magnesium powder for my reef tank, can i use it for my planted tank or is it totally different?


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## Hanuman (28 Mar 2022)

@Zeus. and @Happi. You are both correct. The problem is the unit and the fact that Red Sea did a rough approximation of what Liters are in Gallons or vice versa. Technically 100 L = 26.4172 Gal (or inversely 25 Gal = 94.6353 L) but I assume, for the sake of simplicity, that Red Sea simplified that to 100 L = 25 Gal. See below.

Reconciled. Now you can hug.


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## Happi (28 Mar 2022)

Hanuman said:


> Reconciled. Now you can hug.


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## Zeus. (28 Mar 2022)

Hanuman said:


> @Zeus. and @Happi. You are both correct. The problem is the unit and the fact that Red Sea did a rough approximation of what Liters are in Gallons or vice versa. Technically 100 L = 26.4172 Gal (or inversely 25 Gal = 94.6353 L) but I assume, for the sake of simplicity, that Red Sea simplified that to 100 L = 25 Gal. See below.


Well spotted 😁, it doesn't help when there's Imperial Gallons and US Gallons as well, at least litres are the same volume throughout the world.  
At least we wasn't ranting about our different results


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## Hanuman (28 Mar 2022)

@Zeus. you know far too well what I think about imperial units.... 😅


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## Zeus. (28 Mar 2022)

Hanuman said:


> @Zeus. you know far too well what I think about imperial units.... 😅


That will be the French man coming out in you 🤣 But metric all the way in my book - well except for 'miles per gallon' never got on with 'km/litre'. We are just as bad in the UK as we drive in miles and buy fuel in litres, although I think they only changed to selling fuel in litres as it sounds less putting tax on fuel up 5 pence per litre than say 20 pence per gallon - which the later is less.


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## X3NiTH (28 Mar 2022)

Definately a blend of Sulphates and Chlorides of Magnesium, no Hydroxides as there would be a warning in the MSDS but there is none. I suggest that if it is a blend rather than straight up one ingredient then it follows this principal “sulphate/chlorinity ratio of 0·14000 ± 0·00023” which is the ratio of Sulphate to Chloride in Seawater. I have the liquid supplement to hand but not the dry powder so I can’t check for blend consistency or hygroscopicity.


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## Zeus. (29 Mar 2022)

X3NiTH said:


> sulphate/chlorinity ratio of 0·14000 ± 0·00023” which is the ratio of Sulphate to Chloride in Seawater.


So if we are using MgCl2.6H2O and MgSO4.7H2O as our salts (the little yellow box is the  sulphate/chlorinity ratio of the dose)



Any other salts which are added eg 'calcium' just need to have the same sulphate/chlorinity ratio and we will have a clone of sea water with the correct  sulphate/chlorinity ratio.


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