Calculating HCO3

Physics, chemistry and biology of brewing. The causes and the effects.

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Calculating HCO3

Postby SurfNBrew » Wed Jan 04, 2012 10:47 am

I live in Manchester, England, and unlike most of England, Manchester actually has very soft water. I have recently started getting more involved in the specifics of my brewing to maximise flavour control. However, after looking at the very detailed water report from my local supplier, I noticed there was no mention of CaCO3 or Alkalinity. Here is what *is* in my water report:

Calcium (ppm) - 8.8
Magnesium (ppm) - 1.51
Total Hardness (mg of Ca per L) - 11
pH - 7.42
Total Organic Carbon (mg of C per L) - 1.02
Sulphate (ppm) - 14.0
Sodium (ppm) - 7.83
Chloride (ppm) - 7.1

Is it possible for me to calculate CaCO3 or Alkalinity from these? I've been digging through my BTP programme and How To Brew (Palmer) and Designing Great Beers (Daniels) and can't find anything. Also, realise the oddity that Total Hardness is expressed as concentration of Ca, but doesn't match the value for Ca given as well. Could this value (Total Hardness) be what I'm looking for? Or do I need to contact my water supply company and ask them for a CaCO3 of Alkalinity value?

My next brew will be an Imperial I.P.A., but I brew everything from Pale Ales to Stouts and everything in-between, so I want to be able to adjust my mash water accordingly.

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Manchester water

Postby slothrob » Wed Jan 04, 2012 6:49 pm

I suspect, based on the slightly higher level of Ca than me, that you will have proportionately higher CO3, so your water might have around 10-20 ppm CO3. I'm pretty sure it's going to be very low.

Short of getting the information from your water supplier, which they would probably be glad to give you, you could try downloading the Bru'n Water spreadsheet and playing with the CO3 value until the water is described as "balanced". I've never tried that, but I think it might give you a reasonable estimate.

I believe that the reason that the Calcium and Total Hardness "as Ca" don't match is that the Total Hardness essentially includes the hardness contribution from both the Ca and Mg.
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