Ward Labs report and EZ water calculator

[eastoak]

the EZ water calculator has two radio buttons when inputting the water profile, one says bicarbonate HCO3 ppm and the other says alkalinity CaCO3. it's not really clear to me which of the two i should be using and there seems to be a difference in the final output depending on which one i choose.

pH 8.4
cations / anions, me/L 4.7 /4.3

sodium 35 ppm
potassium 2 ppm
calcium 37 ppm
magnesium 15 ppm
total hardness, CaCO3 155
sulfate, SO4-S 14 ppm
chloride 16 ppm
carbonate 12 ppm
bicarbonate 154 ppm
total alkalinity 147 ppm

 

[mabrungard]

Since this water has a bit of carbonate, it would be best to use the alkalinity value and it would include the sum of the bicarb and carbonate contributions.

 

[eastoak]

Since this water has a bit of carbonate, it would be best to use the alkalinity value and it would include the sum of the bicarb and carbonate contributions.

thank you.

 

[ajdelange]

it's not really clear to me which of the two i should be using and there seems to be a difference in the final output depending on which one i choose.

It shouldn't make any difference as one can calculate bicarbonate and carbonate from alkalinity and pH and alkalinity from bicarbonate at pH. Many of the spreadsheets use a simple approximation (bicarbonate = 61*alkalinity/50) irrespective of pH and that works quite well until pH starts to get into the region where your pH falls. Given your alkalinity (147) and pH the actual bicarbonate level is 175 and the carbonate 2.3 mg/L (Ward labs always bobbles the carbonate calculation for some reason). To begin with someone (either you or Ward Labs) fat-fingered the bicarbonate number. 154 does not correspond to alkalinity of 147 whether you use the exact or approximate interconversion method. If you are entering 154 as bicarbonate or 147 as alkalinity then alkalinity is definitely the number to use as 154 is clearly in error and would certainly be expected to lead to a discrepancy in the 'final output'.

Using the approximation one would calculate 179 for the bicarbonate which would make the carbonate 1.9 mg/L. That's not a lot of difference in the bicarbonate (which is why this approximation is so widely used) so you shouldn't be getting much difference in the 'final output' assuming that you have the choice of the alkalinity or a more correct bicarbonate number but you don't say what the final output is. We can tell just by the fact that there is a difference in the 'final output' that the spreadsheet calculates approximate values or, put another way, that the models are not precise. Given that and the small difference in the precise conversion and the conversion I presume is being used I'd say it doesn't make much difference which you use. One 'final output' will be closer to truth than the other but I'd have to know what the final output is and the details of how it is being calculated (there are other approximations in use too - this is a simple spreadsheet) in order to determine which of the two

 

[eastoak]

thanks ajdelange. it looks like i overstated the difference, i was at work when i posted and just remembered there was some difference but not much of one. the residual alkalinity does vary more between the two, does that matter? most of my grain bills are this simple; 2 row and a bit of crystal or cara pils. i try to use acid malt to bring down the Ph with 1 or 2 grams of salts. for the beer i brew it would seem that my water is near perfect, or am i missing something?

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this is the report from Ward they do have the bicarbonate as 154.

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[eastoak]

the images are too small to read but if you click on the picture, not the little bar on top, it will show you the larger image in smugmug.

 

[ajdelange]

As you are using sauermalz that is likely swamping the alkalinity of the water and this is why it doesn't matter if you change the effective alkalinity to the value implied by the bicarbonate even though we know the bicarbonate number to be incorrect. Ward Labs obviously transcribed a number wrong. I always assumed their process was automatic i.e. a digital titrator would sent the alkalinity and pH numbers to a computer under your sample number and the computer would combine that data with similar messages from an ICP machine but that is pure speculation on my part. Any way, 154 is wrong for the bicarbonate. Use the alkalinity number.

 

[eastoak]

As you are using sauermalz that is likely swamping the alkalinity of the water and this is why it doesn't matter if you change the effective alkalinity to the value implied by the bicarbonate even though we know the bicarbonate number to be incorrect. Ward Labs obviously transcribed a number wrong. I always assumed their process was automatic i.e. a digital titrator would sent the alkalinity and pH numbers to a computer under your sample number and the computer would combine that data with similar messages from an ICP machine but that is pure speculation on my part. Any way, 154 is wrong for the bicarbonate. Use the alkalinity number.

thank you, i appreciate the help. i've been slowing reading and trying to learn more from the new water book, thank you for that too.