Why is there a 3/1 ratio of Ca to Mg? - The Planted Tank Forum
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post #1 of 17 (permalink) Old 12-06-2006, 12:14 AM Thread Starter
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Why is there a 3/1 ratio of Ca to Mg?

Is there a reason we use a 3/1 ratio? I did a search but really couldn't find anything. Why 3/1? why not 2/1? I realize that 4/1 is also fine, but why keep a ratio? If we do not, is it detrimental?
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post #2 of 17 (permalink) Old 12-06-2006, 12:42 AM
 
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3/1 Ca Magnesium

Because it represent an approximation of the two elements in natural freshwater.


We understand that even in nature big variations can occurs but this give a good starting point.
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post #3 of 17 (permalink) Old 12-06-2006, 12:47 AM Thread Starter
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OOOOH ok I see. Is it detrimental to NOT keep this ratio?

I ask because I was using a 2/1 ratio, but have started a 3/1 ratio because everyone else does.
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post #4 of 17 (permalink) Old 12-06-2006, 04:31 AM
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Perhaps I fly contrary to most on this one, but so long as they are there in abundance, why should the ratio really make any difference? Unless either element is being completely used up, why should it make a difference?
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post #5 of 17 (permalink) Old 12-07-2006, 11:16 PM
 
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OK, at the risk of coming across as a big dummy, which I am being new to the EI method and dry ferts, how do you even know what the ratio is? I believe there is a test kit for calcium, but I thought there was not one for magnesium? I read on Rex Grigg's website under Water Chemistry that the "recommended levels of magnesium are 5-10 ppm." How would you know?
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post #6 of 17 (permalink) Old 12-08-2006, 03:03 AM
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The ratio is just what is present in a wide number of aquatic plant species and then averaged.

I looked up about 30 species and compared their Ca/Mg ratios.
The GH booster is a reflection of that ratio according to Greg Watson.

So if you add about 2-3 GH once a week, you will always have plenty of GH, if your tap has more, no problem.

BBS: you are quite correct, it makes no difference. Some enjoy arguing that it does, when they lack the control to maintain the other nutrients and thus cannot rule out a confounding factor in their conclusions.

Every single study I've ever found suggest as long as huge extremes are not done, the ratio of Ca.Mg does not matter in any horticultural setting I am aware of.




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post #7 of 17 (permalink) Old 12-08-2006, 03:51 AM Thread Starter
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Wait, you have to add GH booster? I add magnesium and calcium for my GH once a week in the new RO water for the water change. I had no idea I had to add it multiple times!

Now I gotta stress out over adding more chemicals and lose sleep....
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post #8 of 17 (permalink) Old 12-08-2006, 02:02 PM
 
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OK, still confused!?!?!? If I understand correctly (i.e., gH is the sum of Ca/Mg), and you have a gH reading of between 3-6 ppm, then you most likley do not need to make supplemental Ca and Mg dosing, correct?
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post #9 of 17 (permalink) Old 12-08-2006, 04:22 PM
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Originally Posted by Lazy J View Post
OK, still confused!?!?!? If I understand correctly (i.e., gH is the sum of Ca/Mg), and you have a gH reading of between 3-6 ppm, then you most likley do not need to make supplemental Ca and Mg dosing, correct?
You don't sound confused to me ! Yep, so long as your gH >=3, you 'typically' don't have to worry about Ca/Mg.
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post #10 of 17 (permalink) Old 12-08-2006, 06:12 PM
 
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Confused only in my own mind! Just want to make sure I am doing this dosing thing correctly so as to not make my tank a toxic waste dump.

Thanks for the confirmation.
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post #11 of 17 (permalink) Old 12-08-2006, 06:35 PM
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Originally Posted by justlikeapill View Post
Wait, you have to add GH booster? I add magnesium and calcium for my GH once a week in the new RO water for the water change. I had no idea I had to add it multiple times!

Now I gotta stress out over adding more chemicals and lose sleep....
No, you can just add ther GH booster and that's all.
Many do not and are fine if their tap's GH has Mg and Ca in it already.
Call and ask them. Adding a little bit extra just in case is fine also.

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post #12 of 17 (permalink) Old 12-14-2006, 01:08 AM
 
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No, you can just add ther GH booster and that's all. Many do not and are fine if their tap's GH has Mg and Ca in it already.
Call and ask them. Adding a little bit extra just in case is fine also.
Tom,

What would you suggest for those of us on well water? Nobody to call!

I have a calcium test kit, but as you probably know, it does not test below 20 mg/L. All I know is that my Ca level is somewhere below 20. Should I be adding additional CA and Mg? Based on the post above, with my gH typically at 5.0 ppm and my kH at 4.5 ppm, I am going on the assumption that no additional supplements are necessary. But, with not enough EI time under my belt, I do not know if the plant deficiencies I am having are Ca, MG, or other. Guess I will error on the conservative side and not make any Ca or Mg supplements until I have conclusively eliminated other possibilities!?!?!?!
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post #13 of 17 (permalink) Old 12-14-2006, 01:25 AM
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Apparently most plant deficiencies are CO2 deficiencies, followed by nitrate or phosphate deficiencies, then the other of those two. So, if we take care of those three, using KNO3 and KH2PO4 for the phosphate and nitrate, and we dose a trace mix, we are also taking care of the potassium needs, and then the odds are very much in our favor that other deficiencies aren't significant.

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post #14 of 17 (permalink) Old 12-15-2006, 12:39 AM
 
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Ratio Ca/MG

The ratio is based on general testing of natural water.
Natural water have a ratio of around 4:3 (Ca:Mg)

GH =
Ca= 56.2%
Mg= 24.7 %
Na= 9.4 %
autres 9.7 %

high magnesium content can contribute to calcium deficiency.

Mother nature have million of years of experience. For what going against it?
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post #15 of 17 (permalink) Old 12-15-2006, 08:17 AM
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Quote:
Originally Posted by justlikeapill View Post
Wait, you have to add GH booster? I add magnesium and calcium for my GH once a week in the new RO water for the water change. I had no idea I had to add it multiple times!

Now I gotta stress out over adding more chemicals and lose sleep....
You are over thinking this, once a week is fine, adding 2 GH once a week rules out a limitation, it does not mean that your tap has enough/plenty or might be potentially limiting in Ca or Mg or both.

Many tap water's are perfect.
You can test for Gh and then see about testing for Ca and by default, the remainder will supply plenty in most cases.

If you usde RO, then adding Gh booster will address it oncve a week etc if you add 2 degrees worth.

Regards,
Tom Barr




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