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Old 04-16-2011, 05:43 PM   #11
ajdelange
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For each meq dissolved calcium you must have 1 meq of some anion. The choice is pretty much yours. However with nature that anion is largely bicarbonate (with sulfate and chloride being the others). The problem is that you cannot buy calcium bicarbonate so you must make it as nature does and that involves carbon dioxide gas. I'm not sure where your "targets" are coming from but if they are published profiles for brewing cities and valid (a big question) then you can only hit them closely by using carbonic. There is no way to match, say, Burton, water without it. If you decide you want the calcium of Burton water without the bicarbonate then you are not matching Burton water but rather just the calcium of Burton water and some anion, be it lactate, citrate, phosphate, chloride, sulfate, phosphate will have to be there in place of the bicarbonate.

As there is generally no point in trying to match particular water profiles (you can usually make a better beer by not doing that with the exceptions being Pilsen etc) it seems a lot of trouble to go to with little expectation of improvement. If your goal is to see what a genuine Burton ale tastes like as brewed with genuine Burton water then you would have to do the CO2 thing.

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Old 04-16-2011, 06:16 PM   #12
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The water supply for the brewing system is almost softer than Pilsen water profile, the CO2 method is easy enough to do, just looking for a method to do the water profile tuning with dry materials. Might be better to approach this from a aqueous solution addition direction instead of trying to do dry materials, control of liquid additions would be a bit more complicated though. For the most part this a make work exercise to burn up down time on the weekends by writing additional features into the brewing system control software.

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Old 04-18-2011, 07:45 PM   #13
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After spending some time testing the various formulas against the popular water calculation spreadsheets it looks like what I expected is not the same as the applied methods. Calculations for RA tracked with the data presented in the various table entries and calculation spreadsheets, but not when the published formulas presented for all the components in water profiles were used together. I am curious as to which water components are needed to calculate the RA and which to ignore.

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Old 04-18-2011, 08:30 PM   #14
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Residual alkalinity is defined by

RA = alkalinity - (Ca_hardness + Mg_hardness/2)/3.5

Thus the only ions you need to consider in calculating it are

Calcium
Magnesium
Bicarbonate
and
Carbonate.

Hydroxyl ions also contribute to alkalinity for waters of higher pH.

Strictly speaking you need to consider all charged ions in the soup (fluoride, chloride, iron, nitrate, sulfate....) because these effect the activity coefficients of calcium, magnesium, bicarb and carb but the effects are, for brewing water, small enough that these can be ignored. The error introduced is less than that which is associated with not really knowing what the definition of alkalinity is. The lab is required (per Standard Methods) to tell you what pH was used for the end point of the alkalinity titration but I've never seen a report that actually does that.

The problem with the spreadsheets seems to be that they try to extend the concept of RA to mash as well as water. RA was not intended for this but if you can calculate the RA of water with lactic acid added why not for water with the acids contained in malt? The answer lies in the fact that the concept of RA relies on the idea that malt phosphates will react with calcium and mangnesium to release protons and thus acidify the malt (this is where the 1/2 and 1/3.5 factors come into it). The other big problem with the spreadsheets is that they do not calculate alkalinity correctly where bicarbonate or carbonate are involved (or additions of other weak acids such as phosphoric, lactic, citric etc). One can get away with this to a certain extent as long as pH is below 8.3 or so.

One must remember with respect to RA that its value is pretty much limited to comparison of water supplies. The 1/2 and 1/3.5 factors are nominal. Computer simulations of the chemistry of phosphate/carbonate systems shows that these numbers are only realized when certain assumptions are made about the amount of inorganic phosphate released by malt. The same goes for the tie in between RA and knockout wort pH, no not mash pH, knockout wort pH (see Kolbach's original paper at www.wetnewf.org). Again, typical values can be computed but they are for base malt only mashes and, as the brews studied were German, presumably the base malts were Pilsner malts.

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Old 04-18-2011, 10:57 PM   #15
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Thank you for the explanation and the link, it has helped immensely in my understanding of the formulas and chemistry involved, and their relationship. The acidification with dark malts brings up the question of using acidulated malt and the corresponding effect on SG, color, and mash volume when it is added for PH correction. This should be an interesting Ph correction scenario to work out, versus simple acid addition to brewing water, enough to keep me busy for a while working on the formulas and mechanics of this.

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Old 04-24-2011, 01:15 AM   #16
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After some work with the various equations it seems that things are working correctly when the various higher mineralized waters are used. It appears that when there is insufficient calcium and the mash acid value increases the PH changes opposite the direction expected. Have I implemented the wrong formulas or is this just the expected result when residual alkalinity is low.

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Old 04-24-2011, 03:19 AM   #17
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You haven't given me enough to understand your question fully. If you are speaking of the effects of calcium on phosphate containing malt there are 10 simultaneous equations (1 for CO2 partial pressure, 1 for each of the two dissociations of carbonic acid, 1 for calcium carbonate solubility, 3 for the dissociations of phosphoric acid, 1 for calcium phosphate solubility, 1 for charge neutrality and 1 for proton condition) which must be solved and a lot of assumptions must be made. There is no closed form solution for these. OTOH you can get a rough idea of what it going on using Kolbach's RA definition and his observation about pH shift per unit of RA. I assume you mean the latter. This assumes there is an excess of phosphate and should show a decrease in pH whenever calcium is added or bicarbonate reduced (reduced RA) and an increase of pH when calcium is reduced or alkalinity increased (increase in RA).

Can you be more specific as to which equations are giving you suspect results?

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Old 04-24-2011, 01:03 PM   #18
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Here are the equations that I am attempting to use with interesting results in certain situations.

Alkalinity as CaCO3 HCO3 (ppm) Divide by 61 and multiply by 50

RA* = Alkalinity (ppm as CaCO3)* -* 0.714 x Ca (ppm)* -* 0.585 x Mg (ppm)

Roasted malts: AA = 42.3 x Wt

All other malts: AA = 0.356 x Wt x (Lovibond - 1.8)

mash RA = -1.2 + TAA / MWV

pH =* 5.8 +*((.013*mash Ra)+.013) x RA

This seems to work well with harder water than what I am using, as the municipal water source is filtered river water.

Water Quality
units Results
pH SU 7.48
Chloride mg/l 3
Copper mg/l 0.011
Silver mg/l 0.0004
Zinc mg/l 0.05
Calcium mg/l 3.39
Alkalinity mg/l 20
Bi-Carbonate mg/l 16.4
Calcium Hardness mg/l 10.2
Chlorine Residual mg/l 1.3
Hardness mg/l 10.7
Potassium mg/l 0.655
Silica mg/l 12.9
Sodium mg/l 8.3

Thank you for your patience and help with this.

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Old 04-24-2011, 05:37 PM   #19
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AH, OK. Here I step back and say that while there may be a correlation between malt color and its acidity that correlation is so weak (low values of Pearson's r) that malt acidity is not predictable from color. Second, acidity must be expressed as a function of pH - it is not a constant (titration curve). Third, base malt DI mash pH is not a constant but depends on the base malt (while it is around 5.75 for pilsner base malts it is more like 5.6 for pale ale malt). Fourth as RA is defined in terms of how much malt phosphate neutralizes water alkalinity RA for a mash is meaningless. Thus, I don't believe that mash pH can be modeled this simply. I recognize that one could potentially do this if he had titration curves for each malt in the grist but that data is impossible to obtain unless one wants to do the titration on each malt and it is, IMO, much simpler and useful to just take a small portion of the grist, add some water and measure the pH.

The particular equations you have listed represent a model of mash pH as a function of water RA and malt color. Sometimes the model fits what you see in real life. Sometimes it doesn't. That's the best expalantion I can offer as to why you get erratic numbers. All models have their limits and if you go outside those models often collapse, sometimes violently.

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Old 04-24-2011, 05:59 PM   #20
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Thank you for the confirmation of my suspicions, if it looks to good to be true, it probably is not true for all conditions. You mentioned the phosphate extraction from the malt as an alkalinity neutralizer/binder, what would the effect be if the yeast nutrient ammonium phosphate were added to alkaline brewing waters.

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