Can you estimate the Magnesium Level?

I realize it's impossible to tell me the ppm of magnesium in my water but I just got the report from my water company and this is a number they don't test for. I'm wondering if by giving you my other water numbers, there's anyway of guessing a range of magnesium based on the other levels in my water?

My town is known for having very hard water if that helps at all. Here are the numbers that I do know:



Calcium Ca (ppm)- 81 ppm
Magnesium Mg (ppm)-
Sodium NA (ppm)- 20 ppm
Sulfate SO4 (ppm)- 50 ppm
Chloride Cl (ppm)- 30 ppm
PH level- 7.1 to 7.3
Hardness as (CaCO3) 238 ppm
Alkalinity as (CaCO3) 190 ppm

If I had to guess for the sake of adjusting my water for pale beers, what number would you plug in for magnesium?

I sure don't claim to be an expert on this subject (still trying to get a handle on this myself) but I would use 8.6 ppm.

Converting Ca from ppm to "as CaCO3" (multiply by 50/20) gives 202.5 and subtracting that from the total hardness 238 gives 35.5 for Mg as CaCO3. Converting that number to ppm by multiplying by 12.1/50 gives 8.6

I'd like for someone more knowledgeable about this to check if I did this correctly.

DeafSmith said:

I sure don't claim to be an expert on this subject (still trying to get a handle on this myself) but I would use 8.6 ppm.

Converting Ca from ppm to "as CaCO3" (multiply by 50/20) gives 202.5 and subtracting that from the total hardness 238 gives 35.5 for Mg as CaCO3. Converting that number to ppm by multiplying by 12.1/50 gives 8.6

I'd like for someone more knowledgeable about this to check if I did this correctly.

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Thanks for trying to figure this out. I have no idea it it's correct either Can anyone here double check to see if this makes sense? I guess I was thinking it would be higher than that because we are known for having really hard water, but I obviously don't know much or I wouldn't be asking.

Anyone else willing to weigh in here?

DeafSmith said:

Converting Ca from ppm to "as CaCO3" (multiply by 50/20) gives 202.5 and subtracting that from the total hardness 238 gives 35.5 for Mg as CaCO3. Converting that number to ppm by multiplying by 12.1/50 gives 8.6

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Spot on!

ajdelange said:

Spot on!

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Awesome. Thanks to both of you!

So I wanted to make sure I've done this correctly. Based on our discussion here, I've gone through and made the following adjustments to my water for an IPA with an SRM of 11.

Did I do this correctly? Thanks for your patience.

After a dilution rate of 25% distilled water and adding 2 grams of gypsum and 3 grams of calcium chloride I get:

Adjusted Mash:

Calcium 129
Magnesium 7
Alkalinity 143
Sodium 15
Sulfate 96
Chloride 99

Effective Hardness- 96
Residual Alkalinity- 47
Est. SRM Low (9) High (14)
Chloride to Sulfate Raito- Balanced

Does this sound ok for an IPA? Obviously my base water is good for porters and stouts but not pale beers. Is this right or am I a moron?

Anyone willing to check that real quick for me?

Lodovico said:

Anyone willing to check that real quick for me?

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Hmm. Thought I did but I don't see my post. Anyway, if I take your water with 8.7 mg/L Mg, add 1 L DI water to each 3L of your water and add the gypsum and calcium chloride you specified I get:

Ca 111.8
Mg 6.5
SO4 81.9
Cl 80.0
Na 15.0
Alk 129.2
RA 45.7
Hardness 305.7
Eff Hardness 292.3

So some of my numbers agree with yours and some don't. ??

Yes, you could probably do an IPA with a water with RA this high but pH would be towards the upper end of the desirable range. In the UK if they were to brew with this water they would add sulfuric and/or hydrochloric acid to get the pH down to where they would prefer it to be. The product sold over there is called CRS (Carbonate Reducing Solution) but it's not available in the US AFAIK. You could use lactic acid (most conveniently in the form of acidulated malt) understanding that this is not the traditional way for UK style beers but that getting your hands on some acidulated malt is going to be a lot easier than getting your hands on food CRS (or other food grade sulfuric or hydrochloric acid).

You might want to have a look at the Water Chemistry Primer sticky. The bottom line there would be to dilute 6:1 or more (6 parts RO water, 1 part your water), supplement with chloride and perhaps a little sulfate and then adjust sulfate to taste in subsequent brews. pH control would be through sauermalz.

Chloride to sulfate ratio has limited potential application (but it is to this kind of beer) and beer color really has very little to do with it.