Author Topic: question about water profile ppm calculation  (Read 3671 times)

Offline Eudmin

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question about water profile ppm calculation
« on: October 29, 2008, 12:13:57 PM »
I've been trying to figure out what I'm doing wrong with this calculation.  I had previously done it manually, but recently started trying out your software. 

I used the Water Profile tool and just did a sanity check to see if your results correspond to my hand-done results.

I put 1 gm of Gypsum into 1 gallon of water.

Usually ppm is defined as (grams of solute / grams of solution) * 10^6 so I did dimensional analysis to get:

Code: [Select]
1g CaSO4      1gal water               1 liter water
----------    *  ------------------ * ----------------- * 10^6 = 264 ppm CaSO4
1gal water     3.79 liters water     1000 g water

Ca weighs 40g/mol and SO4 weighs 96g/mol so the ppm of Ca is 40/136*264 = 78ppm Ca and the ppm of SO4 is 96/136*264 = 186ppm SO4.

When I use your tool I get  62ppm Ca and 148ppm SO4. 

What am I doing wrong?

Offline Eudmin

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Re: question about water profile ppm calculation
« Reply #1 on: October 29, 2008, 12:28:56 PM »
Actually, table salt and chalk work out right, baking soda is close.  The two numbers add up to 264, as they should.  1gm/gallon of anything = 1000mg/3.79liters = 264 ppm

If your salts split up in solution then the ratios of the two components will scale with their weights, but the sum should come out to 264ppm for 1 gram in 1 gallon of water.

beernut

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Re: question about water profile ppm calculation
« Reply #2 on: October 31, 2008, 02:08:56 PM »
I have been playing around with the water profile because my water supply is rainwater into tanks which is quite soft and benign.  However with the profiler I can't seem to figure out how many gr/L of various minerals I should be adding to match the water of a designated area.  What am I missing.
« Last Edit: October 31, 2008, 02:11:51 PM by beernut »

 

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