"Water For Coffee" book discussion thread - Page 8

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Viernes
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Postby Viernes » Feb 26, 2016, 6:09 am

@welone

If I understand correctly what you posted, and I'm sorry to say this (if I'm wrong I apologize), then the book it's a fail, it have a big mistake. I know people who bought the book (I have it too), and they have made water with the values described in the book as ions to feed their espresso machines with the water !!

DarrenAddy
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Postby DarrenAddy » May 10, 2016, 9:34 am

I think it only fair to point out that the authors have made a "Corrections and Amendments" to Edition One available here: https://github.com/chhendon/waterforcoffee/raw/master/Corrigendum_EDITION_ONE_10_10_15.pdf (since Oct. 15, 2015). For those concerned about copyright issues, the page on waterforcoffeebook.com containing the link above says:
Note that information contained in the corrections is freely available, and it free to share publicly without modification.


I believe that these corrections are incorporated in the the current edition (but won't be able to tell you until my copy arrives).

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homeburrero
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Postby homeburrero » May 10, 2016, 10:17 am

Alas, that 10-10-2015 corrigendum (http://waterforcoffeebook.com/pages/cor ... amendments) is old, and since then the authors have learned a bit more. Not only that the SCAA hardness and alkalinity measures are unquestionably in CaCO3 equivalent units, but also that their own ideal brew zone graphs were developed using standard GH/KH kits and the graph axes should have been labelled in conventional (archaic, they would say) CaCO3 equivalents. This was nicely explained above in the Feb 7 post from welone. The October corrigendum causes confusion because it reinforces the impression that the GH and KH units on the book's ideal brew zone graphs should be interpreted as ppm as ion (Ca++, Mg++, HCO3-) rather than in CaCO3 equivalents. The authors say they will correct that in the 2nd edition, which I thought they were still working on.

Darren:
Are you sure you have ordered a 2nd edition and not the first?

Update/addition: As of August 2016, Christopher Hendon is saying on Facebook Barista Hustle that their 2nd edition should be coming out sometime in 2017.
Pat
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bdswan
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Postby bdswan » May 16, 2016, 4:01 pm

So, is the General Hardness vs Carbonate Hardness chart correct as-is, but labeled with incorrect units (which should be ppm as CaCO3)?

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yakster
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Postby yakster » May 16, 2016, 7:57 pm

Christopher Hendon has a YouTube on how to use the Red Sea or Reef Foundation Pro titration kit to measure water.

-Chris

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homeburrero
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Postby homeburrero » May 16, 2016, 8:02 pm

bdswan wrote:So, is the General Hardness vs Carbonate Hardness chart correct as-is, but labeled with incorrect units (which should be ppm as CaCO3)?

Yes, my understanding is that every graph in the first edition book that shows General Hardness vs Carbonate Hardness should be interpreted to have units in ppm as CaCO3 equivalents. This includes the representation of the SCAA spec as well as their own ideal and acceptable brew zone graphs.

In the Corrigendum they do have a graph of the SCAA standard plotted as general hardness vs carbonate hardness. In that particular case the graph units are in [Ca++] ion ppm on the Y axis and [HCO3-] ion ppm on the X axis.

In Chapter 6 where they are discussing recipes, they are not using ppm as CaCO3 - there they consistently express [Ca++], [Mg++] and [HCO3-] as ppm (mg/L) of the particular ion they are quantifying. They do use the terms GH and KH in that chapter, but there they are using concentration of ion rather than the conventional measurement units of GH and KH. (The conventional units of these 'hardness' measures are gpg, German degrees, French degrees, Clark degrees, mmol/L, mEq/L, or, most commonly, mg/L or ppm as CaCO3.)

Note for sticklers:
KH stands for Carbonate Hardness (in German, Karbonathärte) and strictly speaking is not the same thing as alkalinity. But they do get used interchangeably and for our purposes can be treated as the same thing. The API KH test is a total alkalinity measurement (it simply measures the acid buffering capacity of the water sample.) Also, carbonate hardness is a confusing term because it may not involve any hardness at all - a solution of sodium bicarbonate has 'carbonate hardness' but has zero general hardness. In water reports you generally see the term alkalinity instead of KH.*

GH stands for general hardness, and is a measure of the amount of divalent cations in the sample. Primarily Ca++ and Mg++. GH and 'total hardness' are the same thing. Since it is a measure of the total number of those ions, and not the weight, and since different ions have different weights, it is expressed in these equivalents that can cause confusion until you get used to them. Using the unit of ppm as CaCO3 turns out to be handy because you can divide by 100 to get mmol/L, or divide by 50 to get mEq/L. Also, if you express both GH and KH in ppm as CaCO3 units, you can subtract the KH number from the GH number to get an idea how much of your hardness is so-called permanent hardness (non-scaling hardness) and how much is so-called temporary hardness. (KH/alkalinity is an estimate of temporary hardness when the GH is higher than the KH.)

* {Later addition] And, I should point out that there are two different meanings for the term "carbonate hardness." The common one used by all the aquarium people, most of the beer and coffee people, in the wikipedia definition, and in many of the test kits is synonymous with carbonate alkalinity. It is abbreviated KH. There is an alternative definition where the term carbonate hardness is used to refer to the portion of Ca++ and Mg++ hardness that is associated with carbonates (CO3-- and HCO3-.) This definition is synonymous with "temporary hardness" as it is the portion of the total hardness that might precipitate (produce scale) under heat and pressure. The new SCAE water chart uses that definition. It is a much more sensible definition in that in this case the term simply means what it says - is the actual hardness that is associated with carbonates.

In future posts on this forum I think it best to avoid using the term carbonate hardness when alkalinity, or even when carbonate alkalinity is meant. Not sure what to do about the term KH. It's used by the popular test kits (which measure alkalinity) and is part of the vernacular in coffee water discussions. GH:KH seems to be a handy and frequent shorthand for discussing the total hardness and alkalinity of a water (i.e., a GH:KH of 100:50 is commonly used to describe a water with 100 mg/l total hardness and 50 mg/l alkalinity as CaCO3)
Pat
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yakster
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Postby yakster » May 31, 2016, 7:12 pm

Anyone using the knowledge they learned from this book to make their own custom water? I was, but my Wife took my 'B' bottle of water additions to the BottleRock concert last weekend and I need to wash it up and re-mix my additives again.

Luckily she called me and I let her know not to drink the liquid in there straight, it's supposed to be used at 10% for addition to RO water so she rinsed it out and used the bottle to keep hydrated.
-Chris

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max
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Postby max » Jun 01, 2016, 1:50 pm

yakster wrote:Anyone using the knowledge they learned from this book to make their own custom water? I was, but my Wife took my 'B' bottle of water additions to the BottleRock concert last weekend and I need to wash it up and re-mix my additives again.


I do. I even conducted a small water cupping session with my girlfriend just to try them side by side. I did it unblinded, but she had no idea which water was in which cup. Nevertheless, the difference between tap water, Brita filtered, and my mixture was clear enough for her to find the last. I have mixed water ever since.

I later learned that the tap water contains more or less the right ratio of minerals, so I now just dillute tap water. However, I should probably look at the numbers again to make sure I'm not mistaken, especially since I'm unsure about the unit of concentration used in the official Zürich report.

In my very limited experiments, I've learned that I'm mostly bothered by carbonate hardness, and the difference seems the most apparent with lighter, acidic roasts. Here in Zürich/Switzerland water is on the harder/alkaline side and dark is the norm for roasts. On the other hand, in Stockholm/Sweden the water is soft and roasts lighter (KH: 41 ppm as [CaCO_3]). Maybe the water is what shaped the coffee cultures?

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icantlactate
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Postby icantlactate » Oct 10, 2016, 12:20 pm

Alright guys, I'm about ready to take the plunge into making my own 'bespoke' water but wanted to run my thinking by you guys first:

I'm planning to make 200x concentrate solutions of epsom salt, gypsum salt and baking soda and combine them in various ways with distilled water to get my desired 120 ppm as CaCO3 GH : 60 ppm as CaCO3 KH. I'm planning to use sulfate rather than chloride solutions to eliminate concerns for corrosion in my stainless steel bonavita kettle. I calculated an ~115 ppm SO4 2- which seems okay based on this thread: Boiler-safe level of chlorides (and other compounds) in water.

I haven't done stoichiometry since high school. What do you guys think?

Alex

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homeburrero
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Postby homeburrero » Oct 10, 2016, 3:16 pm

Your calcs and method look fine to me. You came out with the same conversions you see here and in wikipedia for converting CaCO3 equivilents to Ca++, Mg++, and HCO3- ion.


Your method is nice because it is from scratch, and carefully shows cancelling of units in the conversions.

FWIW, note that you could have gotten to your result faster by using a commonly used unit conversion factor to get you from "as CaCO3" to molar concentrations and vice versa:

100 mg/l (or ppm) CaCO3 equivalent = 1 mmole/l of divalent ion or compound
50 mg/l (or ppm) CaCO3 equivalent = 1 mmole/l of univalent ion or compound

(mmol is millimole, 1/1000th of a mole)

These factors are good to 3 decimal places. (If you wanted silly precision you would use 100.0869 (the molar mass of CaCO3) and 50.04345 .)
One reason the unit "as CaCO3" is handy is because it's easy to divide by 100. Often you can do these in your head - divide by 100, then if it's univalent multiply by 2.

Divalent ions and compounds include Ca++, Mg++, CaCl2, MgSO4, MgSO4*(7H20), CO3--, SO4-- ....
Univalent would include HCO3-, Na+ , K+, NaHCO3, KHCO3, Cl- .....

So you can plug in conversion factors like 1 mmol NaHCO3 / 50 mg CaCO3 equivalent to quickly get your calculation into moles.

For your example:
60 mg/l CaCO3 equivalent * (1 mmol/l NaHCO3 / 50 mg/l CaCO3 equivalent) = 1.2 mmol/l NaHCO3
1.2 mmol/l NaHCO3 * ( 84 mg NaHCO3 / 1 mmol NaHCO3) = 101 mg/l NaHCO3
for the 200x concentrate,
101 mg/l * 1g/1000mg * 200 = 20.2 g/l (same as your result)


Note: Another common way to do this would be to use chemical equivalents
50 mg/l (or ppm) CaCO3 equivalent = 1 milliEquivalent/l of any compound. Then convert to mmol using 2 mEq/mmol for divalent and 1 mEq/mmol for univalent ions and compounds.
Pat
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