[Moderator note: This topic was split off from a previous post in: Parent's Choice (distilled water with minerals added) ]

jeffpresso wrote:Why does TWW use calcium citrate in the formula? I understand the use of epsom salt, and potassium bicarbonate, but I wasn't sure why use calcium citrate.

I think they chose it as a nice soluble calcium salt that contains no chloride.** Calcium chloride is a typical choice, and fine for pourover but chloride is anathema to espresso equipment. Calcium citrate also adds acid buffering capacity but I think that may just be a happy accident. Their espresso formula has 20 mg/L (CaCO3 equivalent) of bicarbonate alkalinity from the potassium bicarb, with an additional 20 - 50 mg/L (CaCO3 equivalent) of acid buffering capacity from the calcium citrate depending on how you calculate or measure it.

** Edit addition: It also appears that they initially chose to add that small amount of calcium citrate as an anti-caking agent. That helped in dispensing precise doses into those little packages.

https://weare.techohio.ohio.gov/2018/02/28/third-wave-water-reinvents-the-at-home-coffee/ wrote:The key is in the calcium citrate that acts as an anti-caking agent which prevents clumping. This leads to a homogenous mixture that can be free flowing and packaged for sale.

And

Taylor Minor on Discord Espresso Aficionados" wrote:We use calcium citrate primarily for its anti-caking properties. Once everything is mixed it allows for an easily flowable mixture that can be dosed accurately. Its a big plus that it also provides some elemental calcium to the mixture.

Where do you source calcium citrate if you make your own formulation? I found epsom salt and potassium bicarbonate, but wasn't sure how to get calcium citrate. Is there a good alternative for calcium citrate?

jeffpresso wrote:Where do you source calcium citrate if you make your own formulation?

Bulk Supplements sells a food grade calcium citrate.

You can get calcium sulfate (gypsum) and calcium carbonate from LD Carlson - I think LD Carlson does a far better job of labeling their products for use in water recipes where you need to know how much of what mineral is in the product. But they don't appear to sell calcium citrate.

With all of these, especially with calcium carbonate, you have to take care to use low concentrations that dissolve fully and stay dissolved in the machine.

You can get Calcium Citrate in pill form from drugstores. It is sold as a supplement. Avoid the chewables, fruit flavoured pills, and pills that also contain Vitamin D3 .

Good point. Be careful about quantifying the dose here. A typical supplement pill might say "200 mg from calcium citrate" , and that would be 200 mg of calcium ion, which is about 5 mmol, equivalent to 2500 mg of anhydrous calcium citrate. Note, for comparison, that the TWW formula uses only 300 mg of calcium citrate in their 1 gallon packet.

You can convert calcium ion to units of CaCO3 equivalent by multiplying by 2.5. (i.e., 20 mg/L of calcium ion is equivalent to 50 mg/l calcium hardness as CaCO3.) Be aware that you can make a mix of calcium citrate and potassium bicarbonate, and still have a limescale risk if the calcium and the bicarbonate numbers are high enough.