# Magnesium - dosing once or several times per week



## Flukeworld (20 Nov 2021)

Hello,

I am a bit in doubt about how to dose Magnesium. I want to meet EI target of 10ppm and I see most of dry salts tutorials are mixing Magnesium Sulfate with Macro ferts. Then Macro is dosed between 3 to 6 times per week. 
My macro is already premixed from a friend (has no magnesium) and as magnesium will modify my GH and I would prefer doing the dosing on water change.
Is there any cons on this approach?


----------



## Nick potts (20 Nov 2021)

none that i see, as long as there is enough in the tank for the week's usage you should be good to dose in one go


----------



## ceg4048 (23 Nov 2021)

Flukeworld said:


> Hello,
> 
> I am a bit in doubt about how to dose Magnesium. I want to meet EI target of 10ppm and I see most of dry salts tutorials are mixing Magnesium Sulfate with Macro ferts. Then Macro is dosed between 3 to 6 times per week.
> My macro is already premixed from a friend (has no magnesium) and as magnesium will modify my GH and I would prefer doing the dosing on water change.
> Is there any cons on this approach?


Hello,
          EI really does not specify Mg at all and there are no optimum amounts simply because the levels vary with different municipal water supplies. The 10ppm is very high and there is no way plants require 10ppm of Mg. Is it possible you have misinterpreted the value of 10ppm of MgSO4 as 10ppm of Mg?

None of the trace metals are required in great quantities. It is up to you to determine how much Mg you wish to add - and it certainly doesn't need to be added daily. It can be added on each water change or once a week. Trace metals accumulate in the plant leaves over time, so it is not necessary to obsess over Mg or over any of the other trace elements.

Cheers,


----------



## Flukeworld (24 Nov 2021)

Thanks for the input Clive.
My GH is really low, basically soft water region where tap water is around GH2-3 and KH2. For some time I have been adding Seachem Equilibrium on water change to raise the GH to at least 4 / 4.5. That just because of the livestock which is partially livebearers and reading most plans like at least GH4 and KH4. So, that's my target.

What I know there is very low Mg in my tap water, under 1mg/l, lets say 0.5ppm. Calcium on other hand calculated with this assumption is somewhere 10-14ppm. So, I got the idea my plants may need Magnesium, where Equilibrium has just 2.41% of Mg. Plants are fine, but not perfect. For a second week I am adding half dose Equlibrium and half MgSO4 and I believe I see some improvement.
So, after some reading I bought some MgSO4, which seems much cheaper to use in combination with CaCl2 rather Equilibrium.
Overall, I am on a point where I want to know exactly what I am adding to the water. So, I am trying to go away from commercial products and make my own ferts from salts. I already know what to buy, so next is calculating how much of this and that. I got several calculators online, but the one I loved is the excel "The IFC Aquarium Fertilizer Calculator". 
So, there the option "EI Dosing Full" shows I need to cover those values in ppm:

MgCa10.0030.00

So here we are - I am not sure is 10 too much, I ma just blindly trusting the calculator..


----------



## ceg4048 (25 Nov 2021)

Flukeworld said:


> Thanks for the input Clive.
> My GH is really low, basically soft water region where tap water is around GH2-3 and KH2. For some time I have been adding Seachem Equilibrium on water change to raise the GH to at least 4 / 4.5. That just because of the livestock which is partially livebearers and reading most plans like at least GH4 and KH4. So, that's my target.
> 
> What I know there is very low Mg in my tap water, under 1mg/l, lets say 0.5ppm. Calcium on other hand calculated with this assumption is somewhere 10-14ppm. So, I got the idea my plants may need Magnesium, where Equilibrium has just 2.41% of Mg. Plants are fine, but not perfect. For a second week I am adding half dose Equlibrium and half MgSO4 and I believe I see some improvement.
> ...


Yeah, both those numbers are insanely high, but it doesn't matter though, as none of these numbers will hurt. What's important is to understand how plants use nutrients instead of blindly following some number on a spreadsheet. You can grow excellent plants using numbers 1/100X of that. So for example, if your fish were soft water breeders and  if you wanted to keep the TDS low then you wouldn't want to use those numbers. It's simply unnecessary.
As I mentioned, Ca and Mg as most of the other metals do not travel outside the leaf. They are retained and the amounts accumulate. What you may have seen as an improvement may be something that would have happened any way just due to the accumulation. You can reverse what you added and see if there is a decline. I do this up and down yo-yo of additions to to see if the effect is actually due to what I thought was the cause...

Cheers,


----------



## Flukeworld (25 Nov 2021)

Good food for thought again, Clive. Thanks!
That could even solve my trouble seeing how much hardness will raise with those values. Also I would go cheaper this way by targeting the GH I want instead of blinding going for 10ppm of Mg that proportionally would cost somewhere 3 times the Ca.


----------



## erwin123 (8 Dec 2021)

ceg4048 said:


> Hello,
> EI really does not specify Mg at all and there are no optimum amounts simply because the levels vary with different municipal water supplies. The 10ppm is very high and there is no way plants require 10ppm of Mg. Is it possible you have misinterpreted the value of 10ppm of MgSO4 as 10ppm of Mg?









I've always wondered about the Mg figures in the IFC spreadsheet as they seemed way higher than the Mg content of the all-in-one ferts.

My local tap water report says there is an average Magnesium 1.6mg/L, so I add a little bit, around 4ppm a week.


----------



## dw1305 (10 Dec 2021)

Hi all,


Flukeworld said:


> For some time I have been adding Seachem Equilibrium on water change to raise the GH to at least 4 / 4.5. ......... reading most plants like at least GH4 and KH4. So, that's my target.


I'd take everything you read about plants, <"hardness and buffering"> with a <"pinch of salt"> as well. Companies are very keen to <"sell you products">, but if you have a look at @Roland's tanks, which he runs <"with minimal dKH">, you can see that his plants grow just fine.





Do you have a conductivity (TDS) meter?

cheers Darrel


----------



## erwin123 (10 Dec 2021)

dw1305 said:


> Hi all,
> 
> I'd take everything you read about plants, <"hardness and buffering"> with a <"pinch of salt"> as well. Companies are very keen to <"sell you products">, but if you have a look at @Roland's tanks, which he runs <"with minimal dKH">, you can see that his plants grow just fine.



From the link provided, Roland's GH is 5/6.


----------



## dw1305 (10 Dec 2021)

Hi all,


erwin123 said:


> From the link provided, Roland's GH is 5/6.


Same for the re-mineralising mix at <"James' Planted Tank">, minimal dKH, but a reasonable amount of calcium (Ca) and magnesium (Mg).  Using my <"_plants can't lie_"> method, I'm going to conclude that @Roland <"probably knows what he is doing">, why he is doing it and why it works.

It is the addition of dKH (carbonate/bicarbonate) that raises the pH. Higher pH makes <"many nutrients less available"> and converts more of the <"Total Inorganic Carbon (TIC) into bicarbonate ions (HCO3-)">. The only problem with HCO3- ions is that they can't be utilised as a CO2 source by <"some "soft water" plants">.

I use tap water to <"re-mineralise the rain-water I use">, if it needs it. It is a <"limestone (CaCO3) aquifer supply">, so adds 1 : 1  dGH :  dKH. I don't add a set amount, I just aim to keep in a <"conductivity datum range">.

This works fine for me, I'm a <"pretty lazy aquarist"> and we have a good quality tap supply. If I was a more conscientious plant keeper I would use a combination of calcium chloride (CaCl2.6H2O), magnesium sulphate (MgSO4.7H2O) and potassium bicarbonate (KHCO3) to give me a "designer" remineraliser. I would also use a <"design it your self"> fertiliser mix, rather than using which ever <"terrestrial plant fertiliser"> <"was remaindered at Wilko's">.

cheers Darrel


----------



## Flukeworld (10 Dec 2021)

dw1305 said:


> This works fine for me, I'm a <"pretty lazy aquarist"> and we have a good quality tap supply. If I was a more conscientious plant keeper I would use a combination of calcium chloride (CaCl2.6H2O), magnesium sulphate (MgSO4.7H2O) and potassium bicarbonate (KHCO3) to give me a "designer" remineraliser. I would also use a <"design it your self"> fertiliser mix, rather than using which ever <"terrestrial plant fertiliser"> <"was remaindered at Wilko's">


I am pretty much doing the same for Magnesium Sulfate, Calcium Chloride, except for KH I use NaHCo2 (baking soda) as more accessible product.


dw1305 said:


> Do you have a conductivity (TDS) meter?


I don't. I still cannot understand the use of it. If I put all chemicals I need to reach advised mineralization, what more TDS would give me? My problem is that I don't understand TDS at all, still cant find simple explanation what it would help me for.


----------



## dw1305 (10 Dec 2021)

Hi all, 


Flukeworld said:


> except for KH I use NaHCo2 (baking soda) as more accessible product.


It doesn't make any difference for the dKH, the only reason for potassium bicarbonate is that potassium a macro-nutrient and sodium (Na) isn't.


Flukeworld said:


> I don't. I still cannot understand the use of it. If I put all chemicals I need to reach advised mineralization, what more TDS would give me? My problem is that I don't understand TDS at all,


Have a look at <"Guide to TDS">. 

cheers Darrel


----------



## Carol (10 Dec 2021)

Hi, TDS its totally dissolved solids,which simply explained are the metals,salts etc you find in treated tap water. In UK you can ask your Water Company for a print out of what their water once treated contains . Mine comes out the tap at varying rates but on average 245,some folks in other parts of the country would get 45. 
Now I keep both fish and plants in a very basic way,have done for years,Ive never believed in making some thing easy you do for pleasure,hard. 
I fussed over the marine systems because you have to,testing and adding and useing Reverse Osmosis water to top up the evaporation ,which had a TDS of 0ppm as no way did I want copper ,or aluminium or even nitrate in the tank. 
I just use a good brand of commercial plant food , my main concern has always been in freshwater tanks,the fish ,the plants are just there for the convenience of the fish and to complete a picture. 
Remember everyone wants to sell you something to make your life easier,your hobby better etc…What does your tank look like? Are you happy with it? Take pleasure from it, thats what hobbys are for. Most likely I will get put in the cupboard for a week because of my lax attitude towards “ stuff” ,but chill, life is for being happy. And….if my Bantams dont get with the programme chill is going out the window ,but thats another story lol…
Take care 😀


----------



## Flukeworld (10 Dec 2021)

Thanks Darrel,
I will check the TDS guide link. 
As for the potassium, I use Potassium sulfate already, as I want to keep those things separately, the carbonate hardness and ferts.

As for "easy way" of keeping, Carol, hello  - for me the pleasure is to read, learn and tweak the things by my own. The get joy of seeing the improvements achieved from that rather than buying "magical" commercial products. Which I did for sometime, sure, but now I am all over make-it-at-your-own as much as possible. 

The only thing that scares me if I somehow manage to make "the perfect" environment and the trill to be gone.. The good thing is that in our hobby, the "perfect" does not exists


----------



## Andy Pierce (10 Dec 2021)

10 ppm Mg if you go with the usual MgSO4 ⋅ 7H2O supply, is starting to creep up on the overall solubility limits for the dry salts if you make a 500 ml stock macro solution for 10 ml / 50 L dosing each of 3d/week along the lines of APF-UK (Aquarium Plant Food UK - Home Page) guidance.  I go with 5 ppm Mg with the understanding that this is also very likely in large excess and which does go into solution in the stock bottle with a little gentle encouragement.


----------



## dw1305 (10 Dec 2021)

Hi all,


Carol said:


> my main concern has always been in freshwater tanks,the fish ,the plants are just there for the convenience of the fish and to complete a picture..............Now I keep both fish and plants in a very basic way,have done for years, I've never believed in making some thing easy you do for pleasure, hard.





Carol said:


> ..................Most likely I will get put in the cupboard for a week


No, you are fine, I think a lot of us have a method that works for them in the long term, but you are going to have to sit on the UKAPS <"naughty step">, because actively growing plants aren't a decoration (or is that what you meant?),  they are the single most important factor in maintaining water quality and fish health.

cheers Darrel


----------



## dw1305 (10 Dec 2021)

Hi all, 


Flukeworld said:


> As for the potassium, I use Potassium sulfate already, as I want to keep those things separately, the carbonate hardness and ferts.


It doesn't really matter where the potassium ions (K+) have come from, they are all the same. It isn't really the potassium, I just don't want to add extra sodium (Na) to the tank if I don't need to.   

cheers Darrel


----------



## Flukeworld (10 Dec 2021)

dw1305 said:


> It isn't really the potassium, I just don't want to add extra sodium (Na) to the tank if I don't need to.


Is there anything about the sodium that should concern me?
Cheers Fluke


----------



## Flukeworld (24 Jan 2022)

Its been about 2 months and I see overall improvement after hardening the water with magnesium and calcium (obviously). Also, for the first time I am able to keep alive Molies by hardening the carbonate hardness with sodium bicarbonate. I see only benefits for now from what I am doing by adding Magnesium Sulfate, Calcium Chloride and Sodium Bicarbonate to my soft tap water.
Cheers


----------

