Bicarbonate HC03

[LeeH]

I think alkalinity is measured as Bicarbonate in Brewfarther but both of my water reports measure it as Carbonate CO3

Anyway around this?

[Silver_Is_Money]

The Eq weight of the HCO3- ion is 61.01684, and the Eq weight of CaCO3 is 50.04345, so Alkalinity as CaCO3 = 50.04345/61.01684 x Bicarbonate.

Round it to Alkalinity ~= 0.82 x Bicarb. The flip-side is that Bicarb ~= 1.22 x Alkalinity.

[LeeH]

Hi,

I do not have NCO3, just CO3 on my report.

[McMullan]

Just multiply by 1.22, Lee. That’s going to convert it (to HC03).

[WallyBrew]

That's from the 8th October 2018 and the alkalinity is given as CaCO3 and is 246

So HCO3 will be 246 x 1.22 = 300

[LeeH]

That's from the 8th October 2018 and the alkalinity is given as CaCO3 and is 246

So HCO3 will be 246 x 1.22 = 300

CaC03!

Many thanks all.

Wally, is it time i retested my water?

[PeeBee]

Flippin' carbonate chemistry, it could drive sane people suicidal (I'm immune 'cos I don't come under the "sane" category).

What helped me was getting my head around something like this:

Realising there is virtually no CO3-- in UK tap water certainly helps (it will mainly be HCO3-, UK tap water is generally between pH 7 and 8 ).

"As CaCO3" is only a convenient means of reporting (damn confusing one). Don't try to dissolve CaCO3 in your mash water as that is virtually impossible, but the stuff is inexplicably still sold in homebrew shops as powdered chalk, or limestone.

[LeeH]

The issue is I have no interest in the waterside of brewing, I just use the broad brush strokes of Murphys recommendations.

Something I need to address next year.

[PeeBee]

…
"As CaCO3" is only a convenient means of reporting (damn confusing one). Don't try to dissolve CaCO3 in your mash water as that is virtually impossible, but the stuff is inexplicably still sold in homebrew shops as powdered chalk, or limestone.

Having been very dismissive of "chalk" (CaCO3), I should suggest alternatives.

Calcium Bicarbonate is not an option! Solid CaHCO3 can't exist. A lot of brewers (and brewing water calculators) will use Baking Soda (NaHCO3); but some might worry about the amount of Sodium it adds. There is also Potassium Bicarbonate (https://www.amazon.co.uk/gp/product/B07663RH9N) but I've never seen it on water calculators so a bit of "manual" substitution might be involved (put Sodium Bicarbonate into the calculator then convert it to the equivalent Potassium Bicarbonate). Cost might weigh against using the potassium salt commercially, but it's negligible on a home-brewing scale.

Finally, if needing to increase alkalinity (which is an uncommon need in the UK) there is Calcium Hydroxide (slaked lime) but its use creates a lot of controversy and is a bit of a pain because it must be added to the grain, not the water. It does dissolve though (remember "lime water" in school chemistry classes?) and some water calculators support it.

[McMullan]

Most brewers who use chalk without any perceived problems (notably, a lack of anal retentiveness) tend to use it in the mash, where it isn't so 'insoluble'. Shall I repeat that? In the mash, where it isn't so 'insoluble'. Mainly because it isn't in 'water' as described in chemistry textbooks designed mainly to get students through examinations more than anything else. Enough said, in my opinion. All meltdowns warmly received this time of year. In theory, of course.

[PeeBee]

… In the mash, where it isn't so 'insoluble'. …

I know that. But look back at the OP: "alkalinity is measured as Bicarbonate in Brewfarther but both of my water reports measure it as Carbonate CO3". All these calculators have you assuming you are dissolving the salts in the water. Even Graham Wheeler's calculator requires you to read the "notes" very carefully to get the bit about "chalk". Is it not preferable to consider "chalk" as much use as a chocolate fireguard than come to terms with the water calculators not being as accurate or helpful than might be thought?

Just to be argumentative: Alkalinity isn't "bicarbonate", but for UK tap water it may as well be. "As CaCO3" or "As Carbonate" is just confusing twaddle!

EDIT (parting shot): And the water companies, full of those who've passed their exams, shouldn't put out information to the general public that requires them to have also passed the exams to make any sense of it. rant, rant, rant …

[f00b4r]

You can also get chalk to dissolve under pressure, so a PET bottle, carbonation cap and CO2 supply is another method.

[PeeBee]

You can also get chalk to dissolve under pressure, so a PET bottle, carbonation cap and CO2 supply is another method.

So I understand. But I can't find a breakdown of the mechanisms that make this happen. The same mechanism that will dissolve chalk in the mash no doubt? (Hence, add chalk to the mash not the water - like slaked lime though the reasons may be a little different).

I presume the CO2 under pressure trick will result is a fairly acidic solution of "calcium bicarbonate"?

The extra calcium would be handy, but sodium or potassium bicarbonate must be an easier way of adding bicarbonate.

[McMullan]

You need a 'breakdown of the mechanisms'? You could just set up a mini mash in a saucepan then add chalk. Measure the pH before, during and after. Or you could just launch a rocket on a journey to the moon. Choices, choices!

[Carnot]

I will try and keep this simple. To all intents, calcium carbonate is barely soluble in water. Very roughly 20 mg/L will dissolve in water as the carbonate. In the presence of carbon dioxide more calcium carbonate will dissolve as calcium bicarbonate is formed, which is soluble in the hundreds of mg/L, subject to certain conditions. See the reationship in the previous post by Peebee. I spent my early years as a water treatment chemist. The reason why we use measurements as CaCO3 was for ease of calculation. In my early days we only had simple caculators and ready reckoners so the muliples had to be easy. I performed many tests of alkalinity and hardness determinations every day and we had to do these quickly and accuratley. Since calcium carbonate had a molecular weight of 100 reporting as CaCO3 was like using a common currency, so all measurment were done as CaCO3 (there we exceptions like iron, chromate, copper, etc).
Your question fo why does chalk dissoolve in the mash is a little more complicated and it puzzled me for some time. Why does the addition of calcium lower the mash pH. All was revealed on page 66 of Water. A comprehensive guide for brewers- ISBN 978-0-937381-99-1. The best £14 you can spend on brewing. In short malted barley contains about 1% (10,000 mg/L) phosphate as phytic acid salts( K and Mg). These phytin salts react with calcium, via many pathways, and the net result is that calcium reacts with the phosphate and releases hydrogen ions which depress the pH(increase the hydrogen ion concentration) and also releases carbon dioxide. The calcium carbonate dissolves but the calcium is precipitated as calcium phospate (solubility about 1-2 mg/L) and carbon dioxide is liberated. The net effect is that the mash pH is lowerd BUT the calcium concentration is barely affected. These reactions can only occur in the mash tun and not in the HLT as it is the phytic acid that allows the dissolution of the calcium carbonate and the precipitation of the calcium as the phosphate. I hope that you can follow this but if not then please tell me where I lost you.

I will not labour the point too much, but many, especially Eric, place much emphasis on alkalinity rather than pH. Measuring pH at mash conditions is especially difficult. You need to get your head around pH, which is a measure of the negative log of the hydrogen ion concentration. pH 5 is a measure of 10 power negative 5, which is effectively micro g/L or 10 ppb in old money. in simple words sod all, and that makes accurate determnation a little tricky, especially when dealing with sugary solutions, and also remember that pH is temperature dependent.