# different kinds of magnesium?



## dzoni (Oct 28, 2005)

Hello guys, just a quick question: 

I have 18 mg/l of Magnesium in tap water - is there any possibility that it is not all bioavailable (it doesn't have some chelates like Fe) and I should add some MgSO4?


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## MatPat (Mar 22, 2004)

I would guess that it is all available. Even if only half is available that is still plenty


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## Error (Apr 16, 2004)

Edward told me a while back that his plants seem to prefer MgSO4 to the Mg one usually finds in tapwater (I forget what specific compound it is that is generally in tap water...).

He uses 100% R/O as far as I know, which gives him a lot of control to test these things.

Are you seeing any stunting or curled growth? If not, I wouldn't worry.


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## dzoni (Oct 28, 2005)

Everything is fine in my tank. I was just asking because many aquarists around me with similar Mg content add a lot of MgSO4, so I wanted to make sure that it's useless


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## Edward (May 25, 2004)

We proved that CaCl2 and CaSO4 work better then CaCO3. Not sure about MgSO4 versus MgCO3 though. 
With your already high tap Mg of 18 ppm or 4 dGH I would pay more attention to inorganic NO3, PO4 and K first.


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## Salt (Apr 5, 2005)

How did you prove this? To me, it seems a calcium ion is a calcium ion.

Additionally, the general wisdom of the Europeans is to lower the TDS, which you can do by using CaCO3, MgCO3, and KHCO3 (or K2CO3) to obtain your desired GH and KH levels (eliminates the excess chloride and sulfate ions).

How did you measure the GH and KH? How do you know plants were not responding to the additional KH from CaCO3, as opposed to "preferring" calcium dosed from CaCl2 or CaSO4? Are you saying the extra chloride and sulfate ions are better for plants?

(Not trying to sound accusative, just trying to understand...)


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## Edward (May 25, 2004)

Hi Salt
Thank you for your reply.

How did I prove CaCl2 and CaSO4 provide better conditions then CaCO3? By growing plants in multiple aquariums with RO water for at least 6 months. 

1. Best ...... 6. Worst

1. CaCl2 + CaSO4 + MgSO4, (The best result with PPS Discus Mix)
2. CaCl2 + MgSO4
3. CaSO4 + MgSO4
4. CaNO3 + MgSO4
5. CaCO3 + MgSO4
6. CaCO3 + MgCO3, (The worst)

Very few species show no difference. The most significant difference is with sensitive and so called soft water plants. 

Lowering TDS improves plant health? Yes, I do have the same experience. 

You are concerned about high levels of Cl2 and SO4? I used to be too. Not any longer though because I run some aquariums without water change for long time and see no harmful accumulation. I believe the plants take the extras because both elements are essential nutrients after all. Also, daily dosing of proper amount helps preserving stable and clean water condition. 

GH and KH testing? Simply by Hagen Nutrafin test kits. 

The damaging factor could be the KH in the CaCO3 and MgCO3. Who knows. There is clear evidence that people with lower KH grow plants with less difficulty. So do people with lower TDS. 

Have you tried any experiments with your plants? How did it go?


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