[ultravista]

My Las Vegas water report is:
Calcium (Ca+2): 75ppm
Magnesium (Mg+2): 24ppm
Sulfates (SO4-2): 228ppm
Sodium (Na+): 88ppm
Chloride (Cl-): 92ppm
Bicarbonate / Alkalinity: 138ppm
Hardness Total: 285 ppm

What do I need, and how much of it, to bring hardness up to 750 mg/l?

[hopfenundmalz]

Hardness is dependent on the Ca and Mg.

Gypsum, CaCl2, and Epsom salt will raise the hardness. Why are you targeting such a high number?

[kramerog]

Portland cement could be useful here if you are not trying to make beer.  I'm not sure why you would want to raise hardness to 750 mg/l for beer purposes.

[RPIScotty]

Beware of targeting a specific region or brewery.

[ultravista]

I am looking to improve my Heady Topper clone. Per the Alchemist's water profile, hardness is 750 mg/l.

[RPIScotty]

I am looking to improve my Heady Topper clone. Per the Alchemist's water profile, hardness is 750 mg/l.

Treated or untreated? That may be the municipal water where the brewery is. If that's the case it tells you next to nothing about what the brewery does to treat the water for brewing HT.

[PrettyBeard]

Heady Topper is an interesting beer.  I wonder how much the nucleation points of the torn aluminium tab play in the 'from the can' taste of it. 

I wonder if that's not the reason I generally hate canned beer and soda.  I always chalked it up to aluminium salts, and years of working with metal making me overly sensative.

[kramerog]

750 mg/l of hardness is not the true goal for Heady Topper.  Speculation on homebrew talk indicates that the hardness may be that high for the mash water but the water is very low in minerals for the sparge to arrive at a more sensible overall mineral profile.  I would recommend starting with RO water because your water is too high in chloride to achieve the desired effect.

[narcout]

Well, the equation for calculating total hardness is [(Ca/20)+(Mg/12.5)]*50

Assuming you are going to leave Mg alone and solving the equation for Ca tells you total Ca would need to be 261.6 ppm, so you need to add 186.6 ppm of Ca.

1 gram of gypsum in one gallon of water adds 61.5 ppm of Ca (as well as 147.4 ppm of sulfate).

Divide 186.6 by 61.5, and the result is 3.03. So you need to add 3.03 grams of gypsum per gallon of brewing water to bring your total hardness to 750 ppm. 

Your resulting water profile would be:

261 ppm calcium
24 ppm magnesium
88 ppm sodium
647 ppm sulfate
92 ppm chloride

I've never brewed with a water profile that comes anywhere close to that, but it doesn't look good to me.  Your mash pH will likely be far lower than desirable. 

You could also use magnesium sulfate to get there, but at 24 ppm, your magnesium level is already getting pretty high.  One gram of magnesium sulfate in one gallon of water adds 26 ppm magnesium and 103 ppm sulfate.

Personally, I would ditch the goal of 750 ppm total hardness, and I would either cut that water heavily (like 75%) with distilled water and add back a bit of gypsum (maybe like half a gram per gallon) or start with all distilled or RO water and build from there.

If you don't have one already, consider downloading a copy of Bru'n Water and read the "water knowledge" tab.