[russell]

  Aurora Colorado water report came out, it doesn't show Magnesium. Is there a way to find that out by what is shown on the report? Water calculaters always show Magesium, is there a reason it is not shown on my water report? This report is shown for Brewers and fish tank owners.

Alkalinity (as CaCO3) ppm... 90
Calcium.....41 PPM
Chloride....45 ppm
Conductivity ....478  µmhos/cm
Hardness  (as CaCo3).....103 ppm
Hardness-CA (as CaCO3) 132 ppm
pH .......8.1
Sodium …..43  ppm
Sulfate......71 ppm

[Richard]

Magnesium is an element, so it can't be made from anything else (unless you are a nuclear physicist). None of the information you listed can tell you anything about the magnesium level. Magnesium is a minor actor, but not totally unimportant in brewing. Contact your water supplier to see if they can provide you with more information. Chances are they know the magnesium level but just didn't report it. It might have just been an oversight or error on their part. If they can't help you, you can always send in a sample to Ward Labs and get them to give you a report. They will definitely tell you the magnesium level.

[Robert]

Richard is correct, you can't in this case extrapolate what you don't have from what you do.  But you could initially make a SWAG at the range.  If you try to charge balance what you have -- something like Bru'n Water would be helpful here -- you might be able to determine how much magnesium might have to be there to zero you out.  Presumably there are lots of other minor ions left out, but it could suggest a ballpark guesstimate.   Or follow Richard's suggestions to get a real amswer.

[hopfenundmalz]

Brewers Friend has a lot of profiles. The ones from Aurora CO are in the 8 or 9 range. Ca is similar to yours.

Time of year will cause differences, I didn't see it those balanced.

[dmtaylor]

Magnesium is only important insomuch as you don't have much of it.  Most water doesn't.  You can almost definitely ignore it, and don't add any, and get great results.

[Silver_Is_Money]

You seem to have the hardnesses reversed.  Total hardness is always greater than calcium hardness.

Calcium Hardness = 2.5*~41 ppm = ~103 ppm (mg/L)

Total Hardness = 132 ppm (mg/L)

Total Hardness = (2.5*Ca) + (4.12*Mg)
132 = (2.5*41) + (4.12*Mg)
132 = 103 + (4.12*Mg)
4.12*Mg = 29
Mg = 7 ppm (mg/L)

You have 7 ppm of Mg++