Home Carbonation for Magnesium Water
although this basenote is publicly-visible, some links
and responses may be UIC members-only.
a core supplement in the Undoctored and Wheat Belly programs.
The most well absorbed oral form of it is “magnesium water”,
a home-made solution of magnesium bicarbonate, made from plain milk of magnesia (magnesium hydroxide in water)
and plain seltzer water (carbonated water):
Mg(OH)2 + 2 CO2 → Mg(HCO3)2
In some regions, plain seltzer water can be hard to find. Such products as are
available are often adulterated with flavorants, colorants, sweeteners, and
minerals other than Mg, plus whatever contaminants are in the bottles.
With all-new bottles, mold release agents, plasticizers and polymer out-gas
products are an issue. With re-used bottles, detergent residues may be present.
In any region, retail bottled seltzer water means dealing with retail bottles —
lots of them. They are bulky and inconvenient to buy and lug home.
They take up storage space both full and empty. They have to be disposed of.
Retail seltzer water is also not free, and in some places is relatively expensive.
This article describes an alternative, using a widely-available home carbonator.
This technique can solve an availability problem, and be more economical than
bottled seltzer water, but both benefits assume you already have a supply of
suitable water in the home.
You must have a source of suitable water for this gambit.
Unfiltered public water in most places is unsuitable. Unfiltered
well water is often unsuitable. If you are already buying drinking
water (purified or spring), it will usually be suitable.
Distilled water would work.
In the specific described process, the home already had a reverse
osmosis system for drinking water.
Plain Milk of Magnesia
If you’ve already been making Mg-water, you have this under
control. If not, obtaining a MoM that is just filtered water and
magnesium hydroxide could be more trouble than you suspect.
Quick Reference article would be a source of tips on this.
There are many brands and products on the market. For this article,
a sodastream® FIZZI™ was used (merely
because it, along with a spare CO2 cylinder and 2 spare
bottles, were stumbled upon at a decent price in a regional retail
store). Selection criteria to apply are:
- Are the containers air-tight when mated to the carbonator?
Having a self-sealing cap would be a plus, but is not
strictly necessary. See Step 8 for more info.
- Does a local supply chain exist for exchanging or refilling the
CO2 cylinders? In the case of the sodastream®
brand, cylinder exchanges are widely available at about US$16.00.
Failing that, you’d need some way to refill them ad-hoc.
- Are spare containers available? Sodastream®
bottles expire. For two people, having three 1 liter
bottles is working well.
- Economics: include the up-front one-time expense, periodic
bottle replacement, and the on-going CO2 expense.
Expect it to be break-even
or slightly cheaper than bottled seltzer water, but much more
convenient, and providing nearly complete quality control.
- Support Life: apart from the refill issue, brands have come
and gone. If the home carbonation fad fades (again), they
might all disappear. Check brand history, and user reviews.
The CO2 cylinders are generally at least
for shipping purposes, if not actual hazmats. Delivery to
AK, HI (and islands generally) is either going to be expensive or
slow (surface vessel).
If the carbonator includes a cylinder, is it full-size, or just a
(non-refillable) very low capacity "starter"?
This article is not an endorsement of the specific brand and
product model used. Sodastream® is a very
annoying brand, generally. The various models are confusing to
compare. The documentation is unsurprisingly heavy on safety warnings,
heavy on strident legal claims that may be unenforceable, and
very weak on key details of use, with nothing on theory of operation.
Such as they are, you may not even be able to find
downloadable manuals in your region.
With the sodastream® brand, some machines
accept an optional glass bottle (carafe). The normal bottles
appear to be heavy duty
Sodastream® claims BPA-free, no
phthalates, no PCBs, and no polycarbonate, but says nothing on BPS.
Wider Context Note:
Carbonated beverages are in general discouraged in the
Undoctored and Wheat Belly programs, due
to pH. In the present reaction, pH is neutralized.
But the point here is to expect to have no other use for
one of these appliances.
Steps Used by Author
The specific process presented here is off-schedule for
the appliance used. If you cannot satisfy yourself that
the steps are safe, then only use the carbonator to make
seltzer water, then later use that to make Mg water.
By-the-book may require more CO2.
The problem that the machine maker wants to avoid is a vigorous reaction when
the CO2 is injected, typically resulting
in a major mess when the bottle is decoupled. In more egregious cases,
the bottle could actually rupture. Note from that video that the system is
clearly airtight until the bottle is decoupled.
The Mg(OH)2 + 2 CO2 → Mg(HCO3)2
reaction is not energetic. Indeed, it appears to be a negative pressure
reaction. In any event, we allow it time to progress prior to decouple.
Set the machine up as per manufacturer instructions.
You’ll probably want to wash the bottles.
- Fill the carbonating bottle with suitable water, about half full.
(We use pre-chilled water, and so skip step 5.)
- Add the recipe amount of MoM. For one liter, that would be 22.75 mL.
- Shake the bottle.
- Add more water to the recommended fill line. For our machine, this
seems to be somewhere between the ~~~~~~ fill line printed on the
bottle, and the molded ridge line just above it.
- Unless pre-chilled water was used, put the bottle in the
refrigerator for several hours, but do not freeze. The lower
the temperature of the liquid water, the more CO2
it accepts, and the less lost at decouple.
- Shake the chilled bottle, and couple it to the carbonator.
- Operate the carbonator for a standard charge or slightly higher charge.
For our machine, 3 full presses is standard, and that appears to be sufficient
to react all the MoM, and not result in much residual carbonation.
- Leave the bottle coupled to the machine for at least 20 minutes.
This allows time for the CO2 to react. If you decouple early,
you’re apt to lose a lot of CO2.
- If the reaction has gone as planned, what was white cloudy water is
now clear, with no obvious precipitate at bottle bottom.
- Decouple. Cap. Shake. Ideally store in fridge. If you lay the
bottle on its side, you can more easily check for sediment or
precipitate as you dial in the process.
- Once it’s clear that all the MoM was reacted, the bottle can be
left out at room temperature. If you get a pronounced hiss on
first opening, that may be ambiguous — is CO2
coming out, or, and perhaps more likely, is air going in.
When we decant the Mg-water for consumption, we take that opportunity to
add some ancient
subterranean mined salt
(presently 3 cranks of coarse Redmond Real Salt®)
Adding salt at this point provides a generous amount of nucleation sites
to release most of the remaining unreacted CO2.
Gaming the sodastream® refill model seems to be
a popular pastime. Personally, I find the US$16 cylinder exchange
price to be acceptable, and we have an outlet in a nearby town that
we frequently visit. You might not have that convenience.
I have not looked into fitting specifications, nor refill pressures,
but those would be essential matters if local refill is the only
recourse. If there are fountain pops available in your area, there
has to be a supply chain for food-grade CO2.
The “food grade” bit is important. Industrial and
recreational (paint ball) CO2 may have insufficient
purity, or even have deliberate additives (such as lubricants),
so do your homework before passing gas.
Bob Niland [disclosures]