HCO3 = CaCO3?

Science is not my strong suit. Please don't laugh at me. I'm married to a scientist and I get enough of that at home.

My water report lists "bicarbonate as CaCO3" but BeerSmith is asking for bicarbonate as HCO3. Can one derive the former from the latter? Does any of this really matter since apparently I should be using EZ Water calculator?

Also, is the convention to use averages when determining the constituents of one's water? I live in the Bay Area and my water report lists what sometimes seem a large range of values (but may actually be insignificant...I'm still new at this and trying to figure that out).

Thanks for the help. If any of you need any help with 19th century post-Hegelian German philosophy or the history of Continental political thought I'm your man. :cross:

HCO3 is bicarbonate

CaCO3 is calcium carbonate

https://www.homebrewtalk.com/f36/alkalinity-caco3-99147/

https://www.homebrewtalk.com/f128/total-alkalinity-caco3-function-bicarbonate-hco3-264645/

Maybe these will help.

The molecular weight of CaCO3 is 100. Thus if you put 100 mg CaCO3 in 1 liter of water and bubble carbon dioxide through the water until the CaCO3 is all dissolved you will have dissolved 1 millimole of the stuff. There will be 1 mmol of calcium and 2 mmol of bicarbonate (one from the CaCO3 and one from the CO2 that dissolved it). Because calcium is doubly charged, we say there are 2 milliequivalents of that. Because bicarbonate is singly charged there are also 2 milliequivalents of that. So there are a couple of ways we could describe this solution. We could say is 0.001 M (1 millimole) or 0.002 N (2 milliequivalents). But instead water chemists have for years preferred to refer to the hardness and bicarbonate content in terms of the amount of calcium carbonate, dissolved in natures way, that led to the observed hardness and bicarbonate (alkalinity) and so say the calcium hardness is 100 parts per million as calcium carbonate and the alkalinity (bicarbonate) contents is 100 parts per million as calcium carbonate. Thus 1 ppm as CaCO3 is 1/50 milliequivalent per liter.

The equivalent weight of bicarbonate (the same as its molecular weight because of the single charge) is 61 mg/mEq. Thus if we have alkalinity of 50 ppm as CaCO3 we have 50/50 = 1 mEq/L and 1*61 mg/L as bicarbonate. Or, put more succinctly ppm_bicarbonate = 61*alkalinity_ppm_as_CaCO3/50.

Don't know why the water industry persists in using ppm as CaCO3. It would be much better IMHO to just use mEq. And I don't know why the spreadsheets insist in asking for mg/L bicarbonate as the vast majority of water reports list alkalinity. To calculate bicarbonate precisely (the 61/50 thing is approximate) you must know pH. The alkalinity number is valid whatever the pH.

I'll get back to you on the Hegel.

[Edit] Forgot the second question: Yes, it is common practice for municipalities to publish average numbers though some also publish fairly extensive monthly data. They all have it - it's a question as to whether they want to publish it or not. Where the water is highly variable as it is in California, this can be a disaster for brewers. They must measure their water parameters every day (and Chico Brewing does this) or wind up making beers which are grossly inconsistent. This is impractical for most home brewers but it can be done. The workaround is to swamp the variations by heavy dilution with low mineral water. See https://www.homebrewtalk.com/f128/my-city-water-quality-report-culver-city-293715/index2.html

The conversion from bicarbonate (as CaCO3) to bicarbonate is to multiply the (as CaCO3) value by 1.22. Bru'n Water has a number of conversion calculators to aid the brewer in getting the right values in the right units in their brewing calculations.

Maybe this is a silly question, but WTF?! If reports provide CaCO3, why does BeerSmith ask for HCO3? Wouldn't it make more sense to ask for the information that's provided?

The lab measures and reports alkalinity as CaCO3. They do not report CaCO3. This is bad enough. The spreadsheet authors are cognizant of the fact that there is in fact very little carbonate in a typical sample as most of it has been converted to bicarbonate and so thought it would simplify things (reduce confusion) if they dealt with alkalinity as bicarbonate. It didn't. It only confused people more. I have always advocated treating alkalinity as alkalinity which is easy to do because you get alkalinity as alkalinity by doubling what's in the report (as CaCO3) and moving the decimal place two placed to the left (e.g. 73 ppm as CaCO3 = 1.46 mEq/L) but I have been ignored. This is all explained in detail in #3. Treating alkalinity as alkalinity makes it fairly easy to understand what is going on - at least relative to the confusion engendered by as bicarbonate and as CaCO3 but the apologists for the as bicarbonate school don't seem to care about that. As you may have guessed getting brewers to think in mEq/L is a mission I have assigned myself so take what I say with a grain of salt.

ajdelange said:

The lab measures and reports alkalinity as CaCO3. They do not report CaCO3. This is bad enough. The spreadsheet authors are cognizant of the fact that there is in fact very little carbonate in a typical sample as most of it has been converted to bicarbonate and so thought it would simplify things (reduce confusion) if they dealt with alkalinity as bicarbonate. It didn't. It only confused people more. I have always advocated treating alkalinity as alkalinity which is easy to do because you get alkalinity as alkalinity by doubling what's in the report (as CaCO3) and moving the decimal place two placed to the left (e.g. 73 ppm as CaCO3 = 1.46 mEq/L) but I have been ignored. This is all explained in detail in #3. Treating alkalinity as alkalinity makes it fairly easy to understand what is going on - at least relative to the confusion engendered by as bicarbonate and as CaCO3 but the apologists for the as bicarbonate school don't seem to care about that. As you may have guessed getting brewers to think in mEq/L is a mission I have assigned myself so take what I say with a grain of salt.

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The report I got lists:
CaCO3 - 90ppm
Alkalinity - 57ppm

So, I guess it depends on where you get your report.

It seems pretty simple to me. Just add more fields to BeerSmith, or make it a drop down selection.

cwmagui said:

The report I got lists:
CaCO3 - 90ppm

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Given that the solubility of CaCO3 in water is about 13 mg/L (ppm) it isn't likely that this means that there are 90 ppm CaCO3 in your water. There is something you are missing. It could be 90 ppm "as CaCO3" (4.5 mEq/L) of total hardness, calcium hardness, magnesium hardness or alkalinity, though that would conflict with your ...

cwmagui said:

Alkalinity - 57ppm

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There is probably some fine print somewhere that explain what CaCO3 - 90 ppm actually means.

cwmagui said:

So, I guess it depends on where you get your report.

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Yes, it does and you have every right to be confused IMO.

cwmagui said:

It seems pretty simple to me. Just add more fields to BeerSmith, or make it a drop down selection.

Click to expand...

It is actually very simple if you use mEq/L as that is the unit in which all calculations have to be done. That should be the unit in which the programs take in alkalinity information (and probably hardness information as well).

I use a cell next to the cell in which you enter the alkalinity number. It lights up with "mmol/L carbo", "mEq/L", "ppm as CaCO3", "dH" etc. according to your selection (with up and down arrows). I do the same for the magnesium and calcium fields and for sulfate (which is sometimes reported as the ion and sometimes as the sulfur in the ion) and nitrate (which is sometime reported as the ion and sometimes as the nitrogen in it).

"ppm as CaCO3" is bad enough but I don't think we'll ever be rid of it any more than the Germans will ever be rid of "dH" because of precedence. I don't think that licenses the spread sheet authors to compound the confusion with their "bicarbonate" but they do because "it works". You have a choice of learning to live with it or doing your own spreadsheet (what I recommend because you will learn so much).

ajdelange said:

Given that the solubility of CaCO3 in water is about 13 mg/L (ppm) it isn't likely that this means that there are 90 ppm CaCO3 in your water. There is something you are missing. It could be 90 ppm "as CaCO3" (4.5 mEq/L) of total hardness, calcium hardness, magnesium hardness or alkalinity, though that would conflict with your ...


There is probably some fine print somewhere that explain what CaCO3 - 90 ppm actually means.
Yes, it does and you have every right to be confused IMO.



It is actually very simple if you use mEq/L as that is the unit in which all calculations have to be done. That should be the unit in which the programs take in alkalinity information (and probably hardness information as well).

I use a cell next to the cell in which you enter the alkalinity number. It lights up with "mmol/L carbo", "mEq/L", "ppm as CaCO3", "dH" etc. according to your selection (with up and down arrows). I do the same for the magnesium and calcium fields and for sulfate (which is sometimes reported as the ion and sometimes as the sulfur in the ion) and nitrate (which is sometime reported as the ion and sometimes as the nitrogen in it).

"ppm as CaCO3" is bad enough but I don't think we'll ever be rid of it any more than the Germans will ever be rid of "dH" because of precedence. I don't think that licenses the spread sheet authors to compound the confusion with their "bicarbonate" but they do because "it works". You have a choice of learning to live with it or doing your own spreadsheet (what I recommend because you will learn so much).

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I feel stumped about the HCO3 value in my water.

I've entered the values I got from the water company, but the value in the HCO3 box is something I calculated and I still don't know if it's correct.

What do I need to do to get my water input right?

Smellyglove said:

I feel stumped about the HCO3 value in my water.

I've entered the values I got from the water company, but the value in the HCO3 box is something I calculated and I still don't know if it's correct.

What do I need to do to get my water input right?

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This is the precise reason I opted to use 100% RO water for brewing years ago. Variable source water properties, outdated and confusing water reports, life is complicated enough. Odds are even knowing how to enter water report information into your calculator the data may not match the actual source water. Just my thoughts, for what it's worth.

Find the total alkalinity on the report. Divide it by 50 and multiply the result by 61. Enter that as the bicarbonate in your spreadsheet. This will be close enough for government work in all cases except where pH of the source water is above 8 or below 6.

To get your water input right you would have to buy a bunch of kits and test it yourself as what the city reports and what comes out of the taps may be quite different depending on the nature of the raw water supply coming into the treatment facility.

ajdelange said:

Find the total alkalinity on the report. Divide it by 50 and multiply the result by 61. Enter that as the bicarbonate in your spreadsheet. This will be close enough for government work in all cases except where pH of the source water is above 8 or below 6.

To get your water input right you would have to buy a bunch of kits and test it yourself as what the city reports and what comes out of the taps may be quite different depending on the nature of the raw water supply coming into the treatment facility.

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Ah! Thanks. Awesome. Total alk is 42. So 51.24. Thanks!

ajdelange said:

Find the total alkalinity on the report. Divide it by 50 and multiply the result by 61. Enter that as the bicarbonate in your spreadsheet. This will be close enough for government work in all cases except where pH of the source water is above 8 or below 6.

To get your water input right you would have to buy a bunch of kits and test it yourself as what the city reports and what comes out of the taps may be quite different depending on the nature of the raw water supply coming into the treatment facility.

Click to expand...

Alkalinity is given as mmol/l. Is this still correct?

The question as as to whether that's mmol as protons (same as mEq) or mmol as bicarbonate which would be different. Perhaps there is some clue in the reports as to what it actually means. Try it both ways. The correct way is the one which gives the best electrical balance for the whole report.

ajdelange said:

The question as as to whether that's mmol as protons (same as mEq) or mmol as bicarbonate which would be different. Perhaps there is so,e clue in the reports as to what it actually means. Try it both ways. The correct way is the one which gives the best electrical balance for the whole report.

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Damn. That's all I got. Sorry to bother you. I know very little about these conversions. I know the conductivity is given as 9,25 mS/m @25C.

Edit. Sorry. I screwed up. It says the total alcalinity is 0.680 mmol/l.

If it's mmol protons then the alkalinity is 34 ppm as CaCO3. If it's bicarbonate then the alkalinity is 41.5. Put those into a spreadsheet to see which gives better electrical balance.

ajdelange said:

If it's mmol protons then the alkalinity is 34 ppm as CaCO3. If it's bicarbonate then the alkalinity is 41.5. Put those into a spreadsheet to see which gives better electrical balance.

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I don't know what electrical balance mean. I do know that when I first tried to dial in my sheet I ended up with 41.5. I will give the water-people where I live a call om monday. Thank you.