Just wanted to share the recipe I have settled on after doing some at home testing with different recipes. I based mine on Lance's Light & Bright, but wanted some mag and sodium as well. This was preferred over the standard light & bright recipe, for me.

Add to one gallon of distilled water:

Calcium - 33 drops
Magnesium - 17 drops
Potassium - 33 drops
Sodium - 9 drops

homeburrero wrote:Beware that the hardness solutions of these concentrates are calcium chloride (CaCl2) and magnesium chloride (MgCl2). For every 10 ppm (as CaCO3) of hardness you are getting 7.1 mg/l of chloride ion. Even at low hardness levels of 20 - 50 ppm as CaCO3 you are looking at chloride levels in excess of what many espresso machine makers advise as the max permissible because of chloride corrosion risks.*

Maybe fine for pourover coffee, but for espresso machines, you're better off avoiding chloride. That's one reason that TWW's espresso formula contains no chloride.

Reviewing the specs for La Marzocco's recommended water formula, it recommends between 0.0 and 0.1ppm total chlorine in the water, but up to 30ppm of chloride.
If this is the case, how would you calculate out the max amount of MgCl2 that would be safe to add if trying to reach 80GH (the barista hustle recommendation)? And if you couldn't reach it with either CaCl2 or MgCl2, it seems like it may be safer using MgSO4 (epsom salt) as the hardness solution in my GS3.

EDIT:
It's been a long time since chemistry class, but here's a rough calculation. Someone correct me if I did it wrong.
Molar mass of MgCl2 (what's in lotus solution) is 95.211g/mol
Molar mass of MgSO4 (what's in epsom salt) is 120g/mol.
1 gram of commercially available epsom salt has 98.6g elemental magnesium in it.
Using the barista hustle water formula for 80GH, that's roughly 0.2g of epsom salt per liter of water.
This is roughly 20mg of elemental magnesium.
Divide this by the molar mass of Mg (24g/mol), multiply by the molar mass of Cl2 (70g/mol) and that's roughly 59mg/L of Cl2.

Assuming my math is correct, this is almost double the recommended limit of chloride to put into a LM machine. This is very disappointing..

maccompatible wrote:And if you couldn't reach it with either CaCl2 or MgCl2, it seems like it may be safer using MgSO4 (epsom salt) as the hardness solution in my GS3.

Yes. Note that the Lotus espresso formula limits the hardness to only 20 mg/L. As discussed above in this thread, Lotus is handy for water experimentation for pourover but in an espresso machine you're better off using Epsom if you want much hardness. The sulfate in Epsom is not desirable but has less corrosion risk than chloride.


Your calculations are on the right track. FWIW I'll add some comments inline:

It's been a long time since chemistry class, but here's a rough calculation. Someone correct me if I did it wrong.
Molar mass of MgCl2 (what's in lotus solution) is 95.211g/mol Yes
Molar mass of MgSO4 (what's in epsom salt) is 120g/mol. Correct for MgSO4, but be aware that Epsom is the heptahydrate with MgSO4*7H20, which has a molar mass of 246.5 g/mol
1 gram of commercially available epsom salt has 98.6g elemental magnesium in it. Typo. Clearly you meant 98.6 mg, which is correct for Epsom (the heptahydrate)
Using the barista hustle water formula for 80GH, that's roughly 0.2g of epsom salt per liter of water. Correct.
This is roughly 20mg of elemental magnesium. Correct
Divide this by the molar mass of Mg (24g/mol), multiply by the molar mass of Cl2 (70g/mol) and that's roughly 59mg/L of Cl2.Yes. Although I think it may be more straightforward to do the chemistry like this:
* 80 mg/L of divalent hardness as CaCO3 is always 0.8 mmol/L (simply divide by 100 to convert "mg/L as CaCO3" to mmol/L for any divalent salt like CaCl2, MgCl2, MgSO4, etc)
* Each MgCl2 molecule contains 2 chloride ions, so 0.8 mmol/L of MgCl2 contains 1.6 mmol/L of chloride ions. The molar mass of Cl is 35.5, and 1.6 * 35.5 = 56.8 mg/L Cl⁻ ion

Thanks homeburrero! I already have high levels of chloride 23! No need to add more.

Tried this the other day for the first time.


Simple and Sweet is a crowd-pleaser recipe that really works with any coffee you throw at it including Sey.


Light and Bright lives up to it's name but I actually didn't like it compared to my usual water which is also 60 ppm nor the simple and sweet recipe. Don't get me wrong, it's good, but it is more one-dimensional and not as balanced. I can see it shining well on really particular coffees but I wouldn't use this for daily brewing or even cupping unless I had another water profile to contrast.

I think the kit itself is nicely priced and perfect as a gift too. I love the freedom this kit gives you and how I can just add a few drops to my coffee itself.

My Lotus Water kit just arrived. I hope to use it to help me understand water recipes better, and my taste preferences against the beans I typically like. At some point I'll run low and probably have a good idea of the recipe I enjoy, and just batch it per typical home barista recommendations!

I have tried to replicate the light&bright for espresso droppers.

I prepare two solutions to match Lotus droppers assuming 20 drops in a ml (0.05ml/drop).

KH
100 ml H20
8.93g Potassium Bicarbonate KHCO3

GH
100 ml H2O
8.56g Magnesium Chloride MgCl2

For 5L of the Light&Bright(Espresso) (20 ppm GH/45 ppm KH) I use:
- 1.1ml of the GH solution
- 5ml of the KH solution

According to Lotus website the water has the following weights, which I think I match on paper.
(mg/L)
Mg: 5
K: 35
Cl: 14
HCO3: 55

I have some doubts though. For Alkalinity KHCO3 as CaCO3 I understood that to do the same buffering you need double. But for the measurement of KH I should only take the molar weight of HCO3 so 61.017g/mol over 110.12. Is that correct ?

I used this information from Lotus to get to the 100ml concentration:
- GH 1 drop of Magnesium chloride concentrate in 450 mL of water adds 10 ppm as CaCO3 of magnesium hardness, 4.5ppm per drop per 1L
- KH 1 drop of Potassium bicarbonate concentrate in 450 mL of water adds 5 ppm as CaCO3 of alkalinity, 2.25ppm per drop per 1L
- And the ion weight table above to double check my result

Esteve wrote:KH
100 ml H20
8.93g Potassium Bicarbonate KHCO3

GH
100 ml H2O
8.56g Magnesium Chloride MgCl2

For 5L of the Light&Bright(Espresso) (20 ppm GH/45 ppm KH) I use:
- 1.1ml of the GH solution
- 5ml of the KH solution

According to Lotus website the water has the following weights, which I think I match on paper.
(mg/L)
Mg: 5
K: 35
Cl: 14
HCO3: 55

Those values look correct to me, although you don't need any Lotus info to get there. Your GH concentrate, assuming you used anhydrous MgCl2 is 0.90 mol/L and your KH concentrate is 0.89 mol/L. That would be 90000 ppm as CaCO3 for the GH and 44500 ppm as CaCO3 for the KH. (Note that the Mg is divalent so it has twice the amount of CaCO3 equivalents per mole that the KHCO3 has.) I would not conclude that those concentrations match what's in the Lotus bottles, but no matter here since you are weighing and not droppering your concentrates.

Esteve wrote:prepare two solutions to match Lotus droppers assuming 20 drops in a ml (0.05ml/drop).

Did you test the drops per ml for those droppers? I believe they use a finer dropper (closer to 40 drops per ml) for K and for Na than the dropper they use for Ca and Mg.

Esteve wrote:I have some doubts though. For Alkalinity KHCO3 as CaCO3 I understood that to do the same buffering you need double. But for the measurement of KH I should only take the molar weight of HCO3 so 61.017g/mol over 110.12. Is that correct ?

Typo there - molar mass of KHCO3 is 100.12. You clearly did use the correct number in your calculations. For KHCO3 divide the milligrams of mineral added by 100.12 to get your mmol/L value. The molar mass of CaCO3 is 100.09 which happens to be nearly identical to KHCO3, but CaCO3 is divalent neutralizes twice as many molecules. So you multiply the mmol value by 50 to (50.045 if you want silly exactness) get your "mg as CaCO3" value. To get your mg HCO3⁻ value you multiply your mmol value by 61.017.

Thanks!

homeburrero wrote: Those values look correct to me, although you don't need any Lotus info to get there.

I liked the idea of a small concentrate and play with the water recipes. And wanted to keep their number of drops, even though per your comment I see I assumed wrong the drops per ml. Seems a bit silly since it is totally arbitrary.

Also, it was handy to have the ion weights for me to check at the end that I was on the right track, my chemistry is more than rusty...

homeburrero wrote: assuming you used anhydrous MgCl2

How do I know ? I bought a coagulating agent to make Tofu labeled just as magnesium chloride.

homeburrero wrote:Did you test the drops per ml for those droppers? I believe they use a finer dropper (closer to 40 drops per ml) for K and for Na than the dropper they use for Ca and Mg.

No. Was not been able to get hold of it when it came out, and as time passed the impulse to buy it died a bit. Love their packaging and the concept but 100 drops per 5L seems very easy to get wrong.

homeburrero wrote: Typo there - molar mass of KHCO3 is 100.12.

Oops! Yes

homeburrero wrote: So you multiply the mmol value by 50 to (50.045 if you want silly exactness) get your "mg as CaCO3" value. To get your mg HCO3⁻ value you multiply your mmol value by 61.017.

That is where I get confused, for KH I multiply the mmol value by 50 ? And for the weight multiply the mmol value by 61.017 (to get to HCO3: 55) ? I think for my calculations I did the later for KH.

Thanks again!

Esteve wrote:How do I know ? I bought a coagulating agent to make Tofu labeled just as magnesium chloride.

That product is almost sure to be a magnesium chloride hydrate, probably mostly hexahydrate, and probably not very pure at that. It can be hard to tell because even if you buy a mineral supplement they often simply label it as magnesium chloride. Often the answer can be deciphered if the label tells you how much elemental magnesium is in the product. Anhydrous MgCl2 (molar mass 95.2 g/mol) would be 25.5% elemental magnesium by weight. The hexaydrate MgCl2*6H20 (molar mass 203 g/mol) would be 12% elemental magnesium by weight.

Esteve wrote:That is where I get confused, for KH I multiply the mmol value by 50 ? And for the weight multiply the mmol value by 61.017 (to get to HCO3: 55) ?

Yes and yes. The salts (NaHCO3, and KHCO3) in your KH are univalent so you multiply the mmoles by 50 to get CaCO3 equivalents. The salts (CaCL2, MgCl2) in your GH are divalent so you multiply the mmoles by 100 to get CaCO3 equivalents.