# Problem if ca:mg ration 1:1?



## IUnknown (Feb 24, 2004)

So I finally got my ca test in. I tested,
GH=136 ppm (7.6 dH)
ca=64 ppm
mg=72 ppm
Do any problems occur when the ca is not higher than the mg (4:3)? The ca has been pretty stable through out the week. I had thought that my plant stunting might have been caused from the ca bottoming out. Now I'm wondering if I was having problems with my No3 testing (I got the Hach kit to double check).
http://aquaticplantcentral.com/forumapc/showthread.php?p=26188#post26188


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## shalu (Oct 1, 2004)

Actually, I don't think your calculation of GH/Ca/Mg is correct. You can read Edward's article in PPS on Ca/Mg calculation. It is not a simple subtraction of Ca from GH. GH is a measurement of equivalent CaCO3, which is 2.5 times Ca in molecular weight. So looks like you have very little Mg in water, actually(the formula actually gives you negative Mg). By the way, what test kits did you buy? I am considering buy some kits too.


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## Edward (May 25, 2004)

Your Mg is zero. See the *Ca:Mg Calculator* in FAQ.


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## IUnknown (Feb 24, 2004)

I sent an email to lamotte to clear things up. I'm using the 4482-DR-LI total hardness kit and using the 3609 calcium hardness kit. I thought that the 4824-DR-LT total, calcium, & magnesium hardness kit was just the previous two kits combined. Maybe I am wrong, because in the combo kit, the instructions to derive mg are just by substraction,
http://www.lamotte.com/pages/common/pdf/instruct/4824drlt.pdf
Maybe the Hagen test kits are different than the lamotte. Where did you get the information for the equation Edward? Could Lamotte have it wrong?


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## shalu (Oct 1, 2004)

I looked through the manual. Look like your readings for Ca and Mg are all for equivalent CaCO3, so your actual
Ca = 64*0.4=25.6 ppm
Mg = 72*0.24 = 17.3 ppm


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## BigFoot (Jan 3, 2005)

Just checking to see if math is correct. My gh is 220 ppm and my ca is 80 ppm (these where tested using hagen) and that should give me a mg = 4.87 is that correct?


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## IUnknown (Feb 24, 2004)

So I am actually low on ca (which would correlate with my observations). Shalu, can you explain what you did. The numbers you multiplied by are molecular weights? Is this an easy chemistry lesson, or is the explanation to lengthy? Why was I wrong, what was the kit actually giving me :???: ?


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## IUnknown (Feb 24, 2004)

Man, I hope adding ca will solve problems in my tank. I've been dealing with this for a long time.


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## IUnknown (Feb 24, 2004)

So using the fertilization, I need to add 16 teaspoons of calcium chloride to add 40 ppm to get the ratio to 4:1? Or is that a different ppm? I guess I will find out after I dose and then test.


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## shalu (Oct 1, 2004)

Greg, the factors 0.4 and 0.24 are in Lamotte manual as well as in Edwards equations. Basically 40% of CaCO3 weight is Ca, and Mg weighs 24% of CaCO3 with same amount of molecules. You apply those factors because Lamotte kits give you numbers in equivalent CaCO3 ppm only, which is also explained in the Lamotte instructions.

Man, 16 teaspoons is awful lot, can't be right. But I am not positive. Which calculator did you use? Currently, I am adding 4 teaspoons of CaCl2 to my 100 gallon tank after each 60% water change, bringing GH from 8 to 13, which helped greatly with my stunting problem.

BigFoot, your Mg number would be right if your Ca=80 is actual Ca, not equivalent CaCO3, not sure what number Hach gives. Actually it is most likely in CaCO3 as well, so in that case, you actually have Ca=32ppm, Mg = 33.6ppm


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## BigFoot (Jan 3, 2005)

Yes it measure in ca not caco3 you have to x it by 2.5 to get the caco3 that is what i read anyway. But what i dont get is how u got my mg = 33.6 i got 4.87.


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## Error (Apr 16, 2004)

I believe the Fertilator is indeed in error--if that's what you used. 16 teaspoons is A LOT of CaCl.

I think this bug was posted in the Fertilator forum a while back, it looks like it hasn't yet been addressed.


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## Edward (May 25, 2004)

IUnknown said:


> I sent an email to lamotte to clear things up. I'm using the 4482-DR-LI total hardness kit and using the 3609 calcium hardness kit. I thought that the 4824-DR-LT total, calcium, & magnesium hardness kit was just the previous two kits combined. Maybe I am wrong, because in the combo kit, the instructions to derive mg are just by substraction,
> http://www.lamotte.com/pages/common/pdf/instruct/4824drlt.pdf
> Maybe the Hagen test kits are different than the lamotte. Where did you get the information for the equation Edward? Could Lamotte have it wrong?


Hi Unknown

No wonder people hate testing after reading this pdf file.

Let's keep it simple:
*1.* Get any basic lfs GH test kit where 1 drop represents 1 dGH or 1 drop x 20 x 0.056 = 1.12 dGH.
*2.* Get Hagen Nutrafin Ca test kit from your lfs. In this kit 1 drop in 10 ml represents 10 ppm of Ca.

Now, you can use the *Ca:Mg Calculator* where;
dGH = drops
Ca = Ca ppm

Example:
GH test kit, 4 drops = *4*
Ca test kit, 2 drops x 10 = *20*
press Calculate
*5.23 * ppm Mg

For dosing calculations wait for the Fertilator version 3 or use tables available at APC FAQ thread, Fertilizing forum.

Edward


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## shalu (Oct 1, 2004)

Edward said:


> Hi Unknown
> 
> No wonder people hate testing after reading this pdf file.
> 
> ...


But why getting the new kits? After reading and understanding the Lamotte PDF, calculating the Ca/Mg is pretty simple and I do believe the resolution of Lamotte is way better. 1 dGh is 17.1 ppm, plus 10ppm on Ca is a lot of wiggle room to accurately determine Mg


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## gnatster (Mar 6, 2004)

> plus 10ppm on Ca is a lot of wiggle room to accurately determine Mg


Double sample size, divide result by 2. Hagen kit is $7.50US at most places. Lamotte a bit more, both however do work.


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## IUnknown (Feb 24, 2004)

OK found my old notes on using turbo calcium (Calcium Chloride),


> I use a bare bones system and add 3/4 tsp baking soda= 6 dh (KH) to 5 gallon jug. 1/2 tsp of magnesium sulfate in 5 gallon will give you 14 ppm mg.
> 
> Turbo Calcium will increase the aqueous calcium concentration in 5 gallons of purified water by 30 ppm; this is about 1/4 teaspoon. Together the mg and calcium give me a GH of 6.


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## IUnknown (Feb 24, 2004)

So, I had some interesting results from adding the Kent turbo calcium. Usually, my tank doesn't really start to pearl until the end of the day. After adjusting the ratio of ca to mg in the tank, the last couple of day the tank has been pearling heavily all day. Lets see if the stunted growth goes away.


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## shalu (Oct 1, 2004)

Greg, that's good to hear. It took three weeks for me to really see a difference in plant growth, so you may have to be a little patient.


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