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What form of Magnesium salt to use in the mash?

My tap water has only 2 ppm Mg, so I’d like to boost it to the minimum level of 10 ppm Palmer recommends. I’ve looked and can’t find Epsom salts locally. The pharmacy says that’s such an old compound that no one uses it any more and they don’t carry it. They have tablets of magnesium citrate, magnesium hydroxide or magnesium carbonate which I would have to crush. Is it even worth the bother? Just realized I forgot to check if there are additional binders in the tablets.

Surely a WalMart has Epsoms salts, check in the foot care section as its used as a soak. Epsoms is mostly a sulfate salt. I think I’d use the hydroxide salt of the three you mention, although at an addition of 8ppm I don’t think any of them would add flavor. The binder would just be a starch, and again probably an insignificant amount and would be converted in a mash.

… I dream of the day that a Walmart open in Finland …

But until then, I live with a very limited selection of what I can buy, which is probably just as well as everything that isn’t a free social benefit (like health care or education) cost 2-3 times what it does in the States.

I’ll see if I can actually figure out the concentration of the MgOH so I can add it intellegently.

Oops sorry I forgot you were across the pond.

The tablets should say what the magnesium content is (not the salt) in milligrams. A ppm is milligrams per liter, so figure out your volume in liters and you know what you need to add. With a 100mg supplement in 5gal= 19L, you’d be adding 5.3ppm. So either use two tablets or go with a 250mg supplement that’ll add 13ppm.

As long as you have even a trace amount of Magnesium your are fine. Between the 2ppm in your water and the amount that’s already in the grain you really don’t have to worry about adding another few ppm.

+1. An all-malt wort will have, at a bare minimum, 100 ppm Mg.

+1. An all-malt wort will have, at a bare minimum, 100 ppm Mg.[/quote]
That’s good to know. I won’t worry about it.

There’s a reason people don’t talk a lot about magnesium additions in beer… it’s not worth it. In the tiny amounts you would need to use to emulate a specific brewing water, it doesn’t affect the flavor or the pH at all, really. Skip it.

Defintely stay away from MgOH as that will actually RAISE your pH, the exact opposite of what you want, and is a somewhat dangerous chemical. People usually use Epsom salt, which is magnesium sulfate. In the old days it was used as a laxative. Nowadays, probably not so much.

FWIW, I add MgSO4 (epsom salts) for flavor ions in the kettle when I want to add sulfate but don’t want to increase the calcium level any further (because I’ve already added either CaCl or CaSO4). That said, I try not to add more than 8-10 ppm of Mg for any beer.

+1. An all-malt wort will have, at a bare minimum, 100 ppm Mg.[/quote]
That’s good to know. I won’t worry about it.[/quote]

Heck, if you wanted to pay the postage ($14 USD), I would have sent you a kilo of Epsom salts.

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