# Reconstituting RO water



## DataGuru (Mar 11, 2005)

Hi all,

A friend of mine has some evil well water. It's loaded with iron and organics. Even with trickling it to precipitate out the iron and PP to clean up the organics, her fancy goldies are still not happy. She's purchased a RO filter and I've been working on trying to build a calculator to make it easy to figure out how much calcium chloride, mag sulfate, potassium chloride and sodium bicarbonate to add to reconstitute the water.

If anyone's geeky with chemistry and has the time to doublecheck my calculations, please take a look and let me know if I've spazzed on anything. It's an Excel spreadsheet.
http://thegab.org/Betty/Calc.xls

The next step after I'm sure this part's happy will be building in some trace elements.

Thanks!
Betty


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## Raul-7 (Feb 4, 2004)

Your link has some extra characters, this one should work: http://thegab.org/Betty/Calc.xls .


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## DataGuru (Mar 11, 2005)

Thanks! 
It's fixed now.


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## intothenew (Aug 1, 2008)

Has any one told you how wonderful you look in that Calc spreadsheet? Marvelous, you look marvelous.



Although I don't understand the calculations yet, I took a copy to try on.


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## DataGuru (Mar 11, 2005)

LOL

hmmm, I wonder if the fertilator would be of any help cross checking it.


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## DataGuru (Mar 11, 2005)

ok. the ppm per dose of Ca, Mg and K agree with Fertilator.

I think what may be messing with my head is that 
1ppm Ca raises GH by about 2.5ppm
1ppm Mg raises GH by about 4.1ppm


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## DataGuru (Mar 11, 2005)

When ppl say they want a 4:1 or a 3:1 ratio of Ca to Mg, are they talking in ppm? or in amount added?

Right now, I'm specifying that I want to add 40ppm Ca and 10ppm Mg.


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## wet (Nov 24, 2008)

Nice spreadsheet! None of the calculations used in the link on your spreadsheet make sense to me and appears to be derived by some inaccurate rules of thumb, especially when 3:1 becomes near 1:1, but mass percentage via your spreadsheet and the Fertilator does.

F22/CaCl is incorrect since you are using hydrated CaCl2, but I think this was a missed entry not called anywhere?

I would not dose NaCl if it was my tank. Whats coming from KCl and sodium bicarb is enough. A suggestion would be for your spreadsheet to sum each of those elements regardless of input source.



> I think what may be messing with my head is that
> 1ppm Ca raises GH by about 2.5ppm
> 1ppm Mg raises GH by about 4.1ppm


Yes, this is confusing, but you'll find many universities and such say GH ppm = (2.5 * Ca ppm) + (4.1 * Mg ppm). I recall Salt posting on APC why this was wrong a couple years ago, and I think I'm a pretty smart guy and everything, but man, that made my head hurt. But you should search if interested.

When I reconstituted RO, I just targeted 40ppm Ca and 10ppm Mg and did not care about d/ppm GH, and would suggest you don't either.  <3



> When ppl say they want a 4:1 or a 3:1 ratio of Ca to Mg, are they talking in ppm? or in amount added?
> 
> Right now, I'm specifying that I want to add 40ppm Ca and 10ppm Mg.


You're right: ppm.

Big fan of your natural tanks and site, by the way... thanks!


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## DataGuru (Mar 11, 2005)

Thanks! Fixed the total weight for CaCl2 2H2O

I think those total hardness ratios are correct. It's the ratio between the weight of that element and the total weight of calcium carbonate. 

But something is still not happy because when I work back from these heuristics, I don't get the same amounts to dose.
1 pound Mag sulfate per 1000 gallons raises GH by 60 ppm (which works out to 0.135443333 grams per gallon to raise GH by 1dh)
1 pound calcium chloride per 1000 gallons raises GH by 120 ppm (which works out to 0.067721667 grams per gallon to raise GH by 1dh)

Well, but I wanna understand and be able to calculate the mix, to know how the water will come out in terms of GH and KH since that's what we can measure. 

Why thank you! NPTs are the bomb!

and thanks for taking the time to double check me! I am so not a chemist.


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## wet (Nov 24, 2008)

Here's those threads. My memory recalls a third but did not find it. Perhaps another read after all these years would help my amateur plant nerd understanding, but I got to Salt's post in the second and got a little dizzy and decided to open another tasty beverage instead... note Laith's formula, too:

http://www.aquaticplantcentral.com/forumapc/showthread.php?t=10973
http://www.aquaticplantcentral.com/forumapc/showthread.php?t=27630

I'm still of the opinion though that its easier to treat Ca and Mg ppm as a target and not worry about that particular test, especially if the KH test verifies the scale and method is working properly.


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## Zapins (Jul 28, 2004)

So if I want to reconstitute 180g of RO water. How much do I add of each for 4:1 ratio? I am keeping discus in the tank so I suppose a low total would be good. Anyone know the "ideal" range for discus?


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## Diana K (Dec 20, 2007)

Discus are OK with very low GH, especially if they are breeding. You may have problems with the plants dying from lack of Ca. They would prefer a GH of at least 3 degrees. 

I would go to those links on the first page of this thread to get some accurate amounts, but perhaps treat a 180 gallon like 3 x your 55 just to be conservative. Test and see if it gets you where you want it.


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