Author Topic: Reading water reports that state "ppm as CaCO3"  (Read 3030 times)

Offline Kit B

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Reading water reports that state "ppm as CaCO3"
« on: December 09, 2011, 08:55:10 AM »
I believe there is some confusion out there, about how to read water reports.
Personally, I think I may have been originally mislead by my utility guy to believe that Ca ppm as CaCO3 = Ca ppm.
After more research, it appears that:
Ca ppm as CaCO3 = (2.5*Ca ppm)
Mg ppm as CaCO3 = (4.1*Mg ppm)

Can anyone verify whether these statements are correct?
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Offline hokerer

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #1 on: December 09, 2011, 09:44:48 AM »
Looks correct according to the "converting between the various units" section of
Kai's "how to read a water report" page...

http://braukaiser.com/wiki/index.php?title=How_to_read_a_water_report
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Offline hopfenundmalz

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #2 on: December 09, 2011, 10:31:39 AM »
There is also a converter in Bru'nwater. 

Back to brewing...
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Offline Kit B

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #3 on: December 09, 2011, 10:38:22 AM »
There is also a converter in Bru'nwater.  

Back to brewing...

Thanks, Jeff.
I realize there are unit conversion options out there.
I'm really making an attempt to understand, rather than blindly punching numbers.

Do any & all items listed as "ppm as CaCO3" need to be converted, based on molar wt?
For example...
Na: 4.35*Na
Cl: 2.81*Cl
SO4: 1.04*SO4
Bicarbonate: 1.67*Bicarb

Is that accurate?
« Last Edit: December 09, 2011, 10:41:33 AM by Kit B »
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Offline hopfenundmalz

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #4 on: December 09, 2011, 11:03:24 AM »
I think that is what you would do.  Didn't do any number crunching.

Ward Labs gives SO4-S, which is SO4 as Sulfur, so you multiply by 3 to get SO4 ppm.

S=32 O=16 so SO4=32+64=96 or times 3. 

Not a chemist, but it is starting to make sense to me also.  Hope this helps.
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Offline denny

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #5 on: December 09, 2011, 11:19:42 AM »
An incredibly useful site for water info is A.J. DeLange's wetnewf.org.
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Re: Reading water reports that state "ppm as CaCO3"
« Reply #6 on: December 09, 2011, 02:22:18 PM »
Do any & all items listed as "ppm as CaCO3" need to be converted, based on molar wt?

Is that accurate?

Yes, but since they don't contribute to hardness or alkalinity it would be strange to report them that way. At that point I'd take a step back and verify that you're getting correct data.
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Offline hopfenundmalz

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #7 on: December 09, 2011, 02:40:58 PM »
An incredibly useful site for water info is A.J. DeLange's wetnewf.org.

I must second this one.  A.J. has been someone talking water chemistry for a long time.

Principles of Brewing Science  by George Fix also had some sections on water chemistry that made a light click on over my head (in the cartoon fashion).
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Offline denny

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #8 on: December 09, 2011, 03:37:37 PM »
An incredibly useful site for water info is A.J. DeLange's wetnewf.org.

I must second this one.  A.J. has been someone talking water chemistry for a long time.

Principles of Brewing Science  by George Fix also had some sections on water chemistry that made a light click on over my head (in the cartoon fashion).

At NHC in Seattle, A.J., Martin, and Colin Kaminski will be doing a panel discussion on water, moderated by John Palmer.  Should be a great seminar!
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Offline musseldoc

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #9 on: December 09, 2011, 03:47:53 PM »
The molecular weight of CaCO3 is 100.0869 g/ml and the molecular weight of calcium is 40.078 g/mol.  For arguments sake, lets round to 100 and 40.  So, if your report reads that you have 100 ppm (mg/l) of CaCO3, then you have 40 ppm (mg/l) of elemental calcium in your water.  Basically 40% of your CaCO3 reading is elemental calcium. 
« Last Edit: December 10, 2011, 04:16:53 PM by Wild Knight »
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Offline hopfenundmalz

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #10 on: December 09, 2011, 09:57:36 PM »
An incredibly useful site for water info is A.J. DeLange's wetnewf.org.

I must second this one.  A.J. has been someone talking water chemistry for a long time.

Principles of Brewing Science  by George Fix also had some sections on water chemistry that made a light click on over my head (in the cartoon fashion).

I have that one already marked on my program as go to.

At NHC in Seattle, A.J., Martin, and Colin Kaminski will be doing a panel discussion on water, moderated by John Palmer.  Should be a great seminar!
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Offline thcipriani

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #11 on: December 10, 2011, 08:15:18 AM »
When you're trying to find the concentration of one substance as another substance you're talking gram equivalent weights.

The equivalent weight of an element can be derived by dividing an element's molar mass by the oxidation number (or, more conveniently, just Google search, "Equivalent weight of x" and you can usually find it. Also, here's a table of equivalent weights: http://www.gewater.com/handbook/control_water_analyses/fig40-2.jsp). In the case of Calcium the equivalent weight is 20.04 (molar mass 40.08 oxidation number 2). 

Once you have the equivalent weight of a substance expressing it as ppm as CaCO3 is the easy part. The equivalent weight of CaCO3 is 50 - that's why everything is expressed as CaCO3 - it's easy! It's like a lowest common denominator.

SO Calcium ppm * CaCO3 equivalent weight / Ca eq weight = Ca as CaCO3

Example:
200ppm Calcium in water expressed as CaCO3:
200 * (50/20) = Ca as CaCO3
200 * 2.5 = Ca as CaCO3
500 ppm Ca as CaCO3

so, yeah, that's right.
« Last Edit: December 10, 2011, 08:29:52 AM by thcipriani »
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Offline musseldoc

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Offline hopfenundmalz

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Re: Reading water reports that state "ppm as CaCO3"
« Reply #13 on: December 11, 2011, 07:35:31 AM »
Tyler and Wild, thanks for the links.  More stuff to read on water chemistry.
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