Treating alkaline water for a dark lager?

I'm trying to treat my water for a bohemian dark lager. My water is rather alkaline with the following composition:

Ca: 70, Mg: 10, Na: 34, SO4: 16, Cl: 60, HCO3: 239.

The water comes from three sources, but their contents are quite close with the exception of Cl, which ranges from 28 to 107. So I just averaged the profiles. Now, my options are boiling the water, adding sauermalz or lactic acid, and adding salts. I don't have a RO source (yet).

I've entered the data into Brun Water water adjustment tab, and obviously can't reach low ion content of Pilzen. So I went with "Brown Malty", and adding 4ml Lactic and 1.1 g gypsym I arrive at:

Ca: 86, Mg: 10, Na: 34, SO4: 55, Cl: 60, HCO3: 75.

I have too much Ca, Mg and Na, but the SO4, Cl and HCO3 are close to the selected profile.

So here are my questions:
1) Does the excessive Ca, Mg and Na matter?
2) Will it even get me CLOSE to something like a bohemian dark lager?
3) If I boil my water instead (possibly with the adition of gypsum), is there a way to calculate the resulting profile?

Thanks, Fisker

The answer to 1) is no. None of those levels are excessive.
For 2), using lactic acid to neutralize that much alkalinity is likely to have a taste impact. I don't think it will be ideal for a dark lager.
3) There is a direct calculation for the decarbonizing effect of boiling. Visit the Water Knowledge page of the Bru'n Water website and go to section 4.2.2 Decarbonization by Boiling. The ending bicarbonate content following boiling should fall between 60 and 80 ppm. That will allow you to calculate what the resulting calcium content is. You would not have to add gypsum to the water to help this reaction. However, adding chalk can help strip out the chalk that is precipitated by the boiling. The other ion concentrations will not be affected by the boiling.

Hi Martin,

Thank you for your answer! Let's see if I get this right (I've added a few new questions below):

mabrungard said:

For 2), using lactic acid to neutralize that much alkalinity is likely to have a taste impact. I don't think it will be ideal for a dark lager.

Click to expand...

So the 4ml Lactic will leave a taste impact that I don't want in my lager. I assume the same holds for the sauermalz and citric acid I have as well. But:

1) Would one be better or worse than the other? Or would there be an advantage to mixing the acid sources, tastewise?

mabrungard said:

3) There is a direct calculation for the decarbonizing effect of boiling. Visit the Water Knowledge page of the Bru'n Water website and go to section 4.2.2 Decarbonization by Boiling. The ending bicarbonate content following boiling should fall between 60 and 80 ppm. That will allow you to calculate what the resulting calcium content is. You would not have to add gypsum to the water to help this reaction. However, adding chalk can help strip out the chalk that is precipitated by the boiling. The other ion concentrations will not be affected by the boiling.

Click to expand...

Ok, so I can get around the carbon reduction by boiling without the negative effect to the taste from the acids. But of course this adds a day to my brewing and is not very environmentally friendly, so if it can be avoided I would prefer to do so. But for now, I'll probably boil the water. With boiling and the same gypsum addition as before, I then arrive at approximately:

Ca: 42, HCO3: 80

This seems to fit the "Brown Malty" cathegory, and I've avoided the acids.

Now, I've come up with a new question regarding the comment to 1):

mabrungard said:

The answer to 1) is no. None of those levels are excessive.

Click to expand...

2) So, the Ca, Mg and Na are fine for my dark lager. But what about the 60 ppm Cl and 55 ppm SO4? As I understand from reading the forum, these ions directly influence the taste. The levels are fine for a "Brown Malty" beer, but far from the Pilzen profile. Should I worry?

And then I start wondering how notable is the taste influence of the acids is compared to that of Cl and SO4, and if they maybe enhance or subdue each other... :cross:

/Fisker

Oh, I just stumbled upon a recent lactate tasting threshold test by Kai Troester here:
http://braukaiser.com/wiki/index.php?title=Lactate_Taste_Threshold_experiment

It seems that sensitivity to the taste of lactate is very individual, but that generally quite high concentrations are acceptable. He recommends a maximum of 400mg/l lactic acid from the test. As my original 4ml lactic acid corresponds to slightly more than 4000mg, and was added to 16L mash water, I'm somewhat below that limit. But his test focuses on light beers. I can only assume that this is because they generally have more acid added to them. Or maybe that darker beers are better at hiding the lactate flavor.

It could be interesting to make the tasting-test myself.

/Fisker