# PPS: Ca/Mg confusion



## modernhamlet (Aug 9, 2005)

Sorry for the multi-part question, but it's all related.

1. If we are seeking to attain a 4:1 balance of Ca:Mg, why do we dose Mg daily without a corresponding Ca addition (of any sort, now that I reread the FAQ...)? Won't this create an imbalance?

2. I have Eco-Complete, which I'm pretty sure is causing a slow increase in KH/GH in my tank. Does anyone know if Eco-Complete leeches both Mg and Ca? In what proportion? 

3. Should I not be dosing the Mg solution if I'm using Eco-Complete?

Thanks in advance for your opinions...


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## BigFoot (Jan 3, 2005)

modernhamlet said:


> Sorry for the multi-part question, but it's all related.
> 
> 1. If we are seeking to attain a 4:1 balance of Ca:Mg, why do we dose Mg daily without a corresponding Ca addition (of any sort, now that I reread the FAQ...)? Won't this create an imbalance?


I cant answer your other 2 qestion as i dont running Eco. Butt i hope to give some insight on this one. You should only add Mg when needed. As for the ratio it is a good way to measure Mg butt I dont think it hurts when your just a little off.


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## Edward (May 25, 2004)

modernhamlet said:


> 1. If we are seeking to attain a 4:1 balance of Ca:Mg, why do we dose Mg daily without a corresponding Ca addition (of any sort, now that I reread the FAQ...)? Won't this create an imbalance?


 The ratio is not necessary. It simply doesn't matter. Both, Ca and Mg contribute to GH, however they are very different in regards to growing healthy plants. Daily Ca dosing doesn't work well. The concentration need to be at least 20 ppm.

The Mg is different. Higher concentrations are unfavorable to many sensitive plants. However some, almost trace like concentrations are necessary.



> 2. I have Eco-Complete, which I'm pretty sure is causing a slow increase in KH/GH in my tank. Does anyone know if Eco-Complete leeches both Mg and Ca? In what proportion?


 There are reported leakages of many elements.



> 3. Should I not be dosing the Mg solution if I'm using Eco-Complete?


 No way to tell over the phone. You need to test it.

Edward


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## modernhamlet (Aug 9, 2005)

Thanks, Edward. Guess it's time to buy a Ca test kit.


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## Little (Oct 18, 2005)

Edward said:


> The Mg is different. Higher concentrations are unfavorable to many sensitive plants. However some, almost trace like concentrations are necessary.
> 
> Edward


What is the concentration from which it is unfavorable?


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## Edward (May 25, 2004)

Little said:


> What is the concentration from which it is unfavorable?


This is not known yet.
It seems that at low KH, amounts of Mg over 10 ppm is causing difficulties. At higher KH, Mg can be much more, but sensitive plants won't grow due to the high KH levels.

Edward


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## modernhamlet (Aug 9, 2005)

Edward said:


> The ratio is not necessary. It simply doesn't matter. Both, Ca and Mg contribute to GH, however they are very different in regards to growing healthy plants. Daily Ca dosing doesn't work well. The concentration need to be at least 20 ppm.
> 
> The Mg is different. Higher concentrations are unfavorable to many sensitive plants. However some, almost trace like concentrations are necessary.
> 
> ...


I finally aquired a Ca test and after a few false starts figure out how to get what I THINK is a reasonably accurate reading.

I got the Salifert test because it had the best resolution. However, even that resolution is pretty lousy if you're not testing for saltwater concentrations. I ended up using 5x the water with the same procedure and then divided the result by 5. Any idea if this was a mistake?

Anyway, the test results I did get last night were:
GH: 8 (143ppm) (API kit)
Ca: 32ppm (Salifert kit)
Mg: 12ppm (as calculated by Edward's PPS spreadsheet)

So am I on target (with a bit high of a GH) or did I just screw up the test? 32 + 12 certainly isn't close to 143.


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## Salt (Apr 5, 2005)

modernhamlet said:


> 1. If we are seeking to attain a 4:1 balance of Ca:Mg, why do we dose Mg daily without a corresponding Ca addition (of any sort, now that I reread the FAQ...)? Won't this create an imbalance?


Good question, why are you?  I use RO/DI water at each water change every week and increase the GH by dosing ca:mg in a 4:1 ratio. I don't dose any more magnesium.



modernhamlet said:


> 2. I have Eco-Complete, which I'm pretty sure is causing a slow increase in KH/GH in my tank. Does anyone know if Eco-Complete leeches both Mg and Ca? In what proportion?





modernhamlet said:


> 3. Should I not be dosing the Mg solution if I'm using Eco-Complete?


I keep seeing this myth crop up that Eco Complete slowly dissolves over time. This is totally untrue. When you first add any uncoated substrate to your tank, it's going to affect water chemistry with any particles that are small enough to dissolve into the water column. Over time after more and more water changes are done, the substrate's effect on water chemistry will decrease. I have read that it's been estimated that sometime between 1-2 years after initial tank setup, whatever nutrients that were available in the substrate will be completely gone... that goes for Eco Complete, Amano soils, etc. At that point your plants pull nutrients from the water column.

I think it was Tom Barr who tested this, perhaps he can chime in with more accurate data...

I use Eco Complete, and for me personally, effect on GH and KH stopped after a month or two.


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## modernhamlet (Aug 9, 2005)

Salt said:


> I use Eco Complete, and for me personally, effect on GH and KH stopped after a month or two.


Good! It is difficult to minimize waterchanges (tap pH 9.3 vs. tank pH 6.9) when the KH and GH keep going up. Hopefully things will ease up after another month or two.


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## houseofcards (Feb 16, 2005)

I currently use eco in my 72 and had corrupted eco in my old 46 and my KH was never above 4, almost always 3. My 72 has only been running about 2 months and I currently have kh 2 to 3 and gh 4 to 5.


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## plantbrain (Jan 23, 2004)

The substrate can be dynamic.
While plants remove nutrients with their roots, there is also detritus breaking down and settling in the lower reaches of the substrate.

So while we might assume that soil/powersand etc is depleted and they are, but there is still some from above as detrital matter and water column nutrients flowing into the substrate over time.

As far as Ca:Mg ratios, there is little evidence the ratios mean anything, terrestiral systems have done 3-4:1 Ca:Mg, but Ca levels change as the plants organ ages, Mg stay the same or declines slightly. Aquatic references have suggested 1:1 ratios for solution based dosing.

Still, finding the levels of Mg and Ca at the low end and the higher range for plants will be useful, it's not clear and testing protocols are dicey for many aquarist methods. This are the last few nutrients folks have not looked at carefully.

KH, Ca, Mg, Cl and SO4.
Traces like Zn, Mn, Cu are still left after that.

No research group etc is going to look at most of the plant species we grow to see what parameters they like and tolerate as far as Mg/Ca/K etc.

Many, if not most substrates tend to have high levels of Ca and Mg. 
So that can complicate some things for some plants and test.

Regards, 
Tom Barr

www.BarrReport.com


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