Holy alkalinity, Danish Batman!

I just moved to Copenhagen and am grappling with the super high alkalinity of the tapwater. The water reports here are insanely detailed and up to date, and according to Bru'n Water my ions balance near perfectly.

But I'm looking at (edit: 380ppm I think and not 549, but still!) 549ppm bicarbonate here. Naturally I want to remove the vast majority of the alkalinity so I can brew Pale Ales and such. The water in Singapore was basically a blank slate but here it is . . . robust. I have attached a screenshot of the basic water parameters.

Sadly, you can't buy RO water by the jug here and I rent, so an RO system will have to wait. I have lactic acid (sold strangely at 80% from maltbazaren.dk) but according to Bru'n, I would need a helluva lot.

So I am looking at boiling 20L or so for 30 minutes and adding the following to that water:
2g CaSO4
2.5g CaCl
2ml 80% lactic acid

I couldn't work this out with Bru'n, but brewersfriend's boil calculator predicted that this should drop nearly all the bicarbonate out of the water. I would then blend the water back 50/50 with my tap water.

And according to Bru'n, I would still need to add a few ml of acid to kill off the remaining bicarbonate to get my mash pH to 5.4. But the ultimate acid use is a fraction of the non-boiling approach.

Are there huge flaws to my plan or is it doable? And should I add the acid before I boil that 20L (my guess is yes)?

Also, is there any way to reduce Chloride without dilution? The water here is way high in it.

You can remove, by boiling, all but 1 mEq/L (50 ppm as CaCO3) of the smaller of the alkalinity or calcium hardness (if calcium hardness is less that alkalinity supplement calcium until it is greater). If you do this you should be left with alkalinity of 1 mEq/L or close to it. This is effectively neutralized by about 0.8 mEq/L acidity so for 20L water you will need about 16 mEq. 88% lactic acid is about 11.8N so for 80% you will need approximately 80*16/(88*11.8) = 1.23 mL. This is an estimate. Do the boil, decant and cool, add the HLac and check pH. Add additional to get to the desired mash pH. Your water alkalinity is 0 at this point and the brew can be designed as if it is being made with RO water.

Thanks!

I have a question. My water report gives a Total Alkalinity figure in mmol/l of 6.2; it also gives some hardness figures.

Can you confirm that I should use the Total Alkalinity figure to determine the proper HCO3 ppm?

I'm not sure that you have input the water report correctly. It shows 6.21 mmol/L alkalinity and that does equate to the 379 ppm bicarbonate value they report.

I note that the report doesn't seem to show the Mg or SO4 levels, or I don't know how to read Norwegian (I don't).

Great, thanks. That makes a lot more sense. That was just a snippet of the report. Mg is given as 25 ppm and sulfate as 99ppm.

Mer-man said:

I have a question. My water report gives a Total Alkalinity figure in mmol/l of 6.2; it also gives some hardness figures.

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Yes, that is the alkalinity in mEq/L (here expressed as mmol/L protons or, in fact, as mmol/L of anything with a unit charge). This is confirmed by the Hardhed, Carbonat of 17 °dH which is equivalent to 6.1 mEq/L (IOW it is, despite its name, actually the alkalinity).

Mer-man said:

Can you confirm that I should use the Total Alkalinity figure to determine the proper HCO3 ppm?

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Yes, you should use that number in your calculations. For example, as you have 140/20 = 7 mEq/L calcium the alkalinity, at 6.1, is limiting so you should be able to soften by boiling down to 1 mEq/L alkalinity removing 5.1 and taking 5.1 mEq/L calcium with it leaving 1.9.

The bicarbonate concentration pretty much immaterial except as a matter of curiosity and it depends, for a given alkalinity, on the pH. The given bicarbonate level in your report tells us the pH is near 7 (or it should be if your utility does the bicarbonate calculations correctly which many don't).

pH Bicarb
6.0 387
6.5 381
7.0 379
7.5 378
8.0 374
8.5 365
9.0 336
etc.

It's hard to say what to do here because some of the popular programs think bicarbonate is the independent variable and deduce alkalinity from it by using bicarbonate as a proxy for it. If you have the option to enter alkalinity as alkalinity do that rather than entering bicarbonate. In any case the errors should be small (unless the water pH is high or low relative to the usual range).

Do we have any data on how much the addition of powdered chalk to the boiling water will speed decarbonation?

I am anticipating boiling for 25-30 minutes, but will happily use powdered chalk if it can significantly speed the process. Chalk being cheaper than gas, and all.

Thanks!

There is some question as to whether it actually speeds decarbonation at all. When CO2 is driven off microcrystals of chalk are formed:

Ca++ + 2HCO3- --> CO2 + H2O + CaCO3

The theory is that if there is a lattice of CaCO3 available the microcrystals will attach to that or form on that faster than they will initially accrete (and thus form nucleation sites on their own).

If the volume of water to be treated is small such that the CO2 readily escapes then the reaction given above actually takes place pretty quickly (driven to the right by the removal of the CO2 per LeChatelier's principle). For a highly carbonaceous water like yours it may not even be necessary to boil if the volume is small enough though steam does sparge out the CO2. I'd expect that bringing the water to the boil should be enough.

Precipitation reactions are difficult to predict accurately so you should really obtain alkalinity (and probably hardness too) test kits and check on what you have after boiling. This also lets you experiment to see whether a longer boil removes more alkalinity or not.

Another thing I forgot to mention in the earlier post: your alkalinity numbers in mmol/L or mEq/L need to be multiplied by 50 before being entered into most US spreadsheets. Thus 6.2 mEq/L is 310 ppm as CaCO3.

mabrungard said:

It shows 6.21 mmol/L alkalinity and that does equate to the 379 ppm bicarbonate value they report.

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310 v. 379 . . . I think that is enough to throw my calculations, isn't it? Which value should I use?

FYI Martin, it's Danish not Norwegian, though if you can read Danish you can read Norwegian.

I would love to test it and know exactly where I get, so I will ask at my homebrew shop if they have a test kit!

Mer-man said:

310 v. 379 . . . I think that is enough to throw my calculations, isn't it? Which value should I use?

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The alkalinity is 6.2 mEq/L (or 6.1 using the 17 °dH). The former amounts to 310 ppm as CaCO3 and the latter to 305. Life would be a lot simpler if everyone used mEq/L as a measure of alkalinity but in North America we multiply those values by 50 to get 'parts per million as calcium carbonate' and most of the US spreadsheets want input in those units. At pH 7 6.2 mEq/L alkalinity implies 379 mg/L bicarbonate ion subject to a bunch of assumptions the most important of which is that there are no other weak acid system ions (such as phosphate) in the water. As I indicated in an earlier post the authors of many spreadsheets and calculators do not appreciate the subtleties of the relationship between bicarbonate ion content, alkalinity and pH and many want you to enter a bicarbonate value (in which case use 379) or give the option of entering bicarbonate or alkalinity (310) by ticking a check box or pressing a radio button.

Mer-man said:

I would love to test it and know exactly where I get, so I will ask at my homebrew shop if they have a test kit!

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A better bet is an aquarium supply store. Aquarists must maintain proper pH, calcium and magnesium content and alkalinity and so suppliers sell test kits for those. There are no test kits for bicarbonate as it is calculated from alkalinity and pH.

As for the language, technical terms are close enough in the Nordic languages to German so it pretty easy to dope out what is intended.

Hey guys

I bought an aquarium test kit that does "carbonate hardness", pH, "total hardness", etc.

I am going to test my water at some intervals of boiling to see how long I need to boil to scrub sufficient bicarbonate.

I will come back with the results. Any advice?

This has been studied. It takes at least 15 minutes of boiling to produce the decarbonation effect and drop the chalk. I'm not sure why it takes so long since the CO2 solubility drops to near zero when the temperature approaches boiling point and it seems that the gas should all leave then. But apparently it does not. Chemical kinetics, I suppose.

In my experience (limited because my water isn't very hard) decarbonation takes place very quickly and it is well known that this is the case with small volumes at least as the water turns milky from suspended calcium carbonate before it even boils in cases where there is a lot of Ca++ and HCO3-.

Dropping of the chalk is another matter. It may take some time for it to precipitate to the point that the treated water is clear (and cool).

I expect that what is involved with large volumes is simply LeChatelier: the carbon dioxide can't get out of the water fast enough and the reaction doesn't, therefore, take place as quickly.

Seems like chalk continues to precipitate for a while. Will it affect the mash if it is on the bottom of the kettle? This happens if I decant off the boiled out chalk and use the water right away.

And for the record, from 17 degrees carbonate hardness:
5 min boil, to 9;
10 min boil to 6
15 min boil to 3.

Carbonate on the bottom of the kettle will, eventually, redissolve as CO2 from the air dissolves in the cool water. This doesn't happen very fast, however.

Ok, so I tested this.

Thanks to boiling, I did not need much more than a little extra calcium in the mash. Based on the consensus that pH strips read 0.3-0.4 low in a mash, I hit a 5.3-5.4 pH.

This was corroborated by me hitting my predicted pre-boil gravity. The last batch my gravity was a bit low! Same grist composition.

Thank you for the information and discussion, AJ and Martin. With your help (and a way to test my results!) I have gotten comfortable using this water.

Cheers!