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Old 08-15-2012, 10:41 AM   #1
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Default EZ Water and Bru"n Water different pH calculation

Finally I bough RO system and I decided to learn more about water chemistry in order to create water profile for my next batch. I read Brun Water Knowledge (which is excelent) and few articles just to get some basics... I am trying to workout my new water profile with RO water using EZ Water and Bru"n Water calculators.

I dont know what am doing something wrong, but it seems that calculators give me different pH value with this water profile and grain bill:

STARTING WATER PROFILE:
Ca- 9 ppm
Mg- 3 ppm
Na- 0.2 ppm
Cl- 1 ppm
SO4- 1 ppm
HCO3- 14.6 ppm

GRAIN BILL:
Pilsner- 8 kg
Wheat- 0.5 kg
Crystal 60L- 0.8 kg

SALTS TO ADD:
CaSO4 (Gypsum)- 3g
CaCl2 (Calc. Chloride)- 6g
MgSO4 (Epsom salt)- 3g
NaHCO3 (Baking soda) Mash only- 2g

MASH pH RESULT:
EZ Water: 5.67
Bru"n Water: 5.3

Also, final sodium concentration is different, according to EZ Water it will be 9 ppm and according to Bru"n Water sodium is 18, even I didnt added baking soda to sparge water.

Any help is higly appreciate.



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Old 08-15-2012, 01:18 PM   #2
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Wish I had a nickle for each time I've answered this one. Calculation of mash is theoretically fairly simple but there are practical difficulties in implementation. AFAIK neither of the two spreadsheets you are comparing uses a 'robust' model as this would required iterative solution and while that is easy enough to do with Excel it's probably not something the casual user will want to be bothered with. Even if they did use the robust model it would be very difficult to obtain the data the robust model requires (which among other things says the robust model isn't that robust). This is because the model needs to know the titration curve for each malt in the grist and that varies with malt type, barley cultivar, moisture content, maltings, crop, batch number and, most significantly, mash time and temperature.

Thus the spreadsheets and calculators must use a much simpler model which approximates the behaviour of, for example, a representative 40L crystal. The models are the province of the spreadsheet creators. Some use measured data, some use correlations with malt color, some have empirical tweaks etc. In modeling there are an infinite number of degrees of freedom. Different model, different results. The democrat's model of Obama care is that it will make excellent medical care available to everyone while dramatically reducing the costs. The republican model is that it will destroy our medical care system and take the rest of the economy down with it [just noticed you are in Croatia so this is probably not a terribly meaningful example to you]. Using that as an illustration makes the obvious question stand out in capital letters: which model do you use/accept/believe? Or should you average the results of the two. In the mash pH model the average of the two is 5.48 and that's about what you would get if you left out the baking soda. With baking soda, the mash pH will be higher - probably closer to what EZ predicts so in this case EZ is probably the better predictor but it is very likely Brun water will be the better predictor in other cases. Your best course is to use both spreadsheets while carefully measuring the actual mash pH you obtain when you brew. You will discover from this process which of the two better models your brewing materials and practices and this may depend on style. In the future you can then use that spreadsheet but by that time you will find the combination of your pH meter and experience more powerful than a spreadsheet and rely on them. Eventually the pH meter will go the same way.

The sodium calculation is very easy for a spreadsheet or calculator so if the two spreadsheets are giving you conflicting answers it's likely you are not entering the same data so check that.

Until such time as you get the spreadsheet thing sorted out you might want to just follow the recommendations of the Primer.

It is most important that you do not add any bicarbonate. This will drive mash pH as high or higher than the EZ prediction. Also there is no need for the magnesium sulfate. You can use some as an additional source of sulfate if you want that but beer generally tastes better with lower magnesium (though it may help you to live longer).



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Old 08-15-2012, 03:39 PM   #3
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Forgot to say, it was 30 L+30 L volume.

I get what you meant, every sheet has its own +/- sides, there is so much environment factors that affects pH and its pretty tough to make realistic calc.
I"ll have to closely learn my sistem to get constant results, and start to add salts part by part and measure pH continously...

Does all salts take same time to disolve and affect pH, or some of them (including acids..?) react differently?
I use lactic acid, and usually I read it 15-20 minutes after doughing in.

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If I could I would get you a beer for this one. Cheers!
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Old 08-15-2012, 05:01 PM   #4
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Most of the salts and acids dissolve and react quickly. The exception is chalk (calcium carbonate) which does take a long time. This is just one of several reasons for not using it except under special circumstances. But then there is the question of what it is reacting with. The material in malt is encapsulated and the capsules must be swollen to the point that they burst and then the liquid (water) bearing the chemicals you added must penetrate and all this takes time. Even if you add just distilled water to grist it will take up to 20 minutes or more for the pH to stabilize. What you are seeing is quite normal.

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Old 08-15-2012, 06:55 PM   #5
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From what I read so far, barely have great impact on what is going on in mash. Correct me if I"m wrong, it seems that the key to get right pH is reaction between Ca and Mg with malt phytin which produces acids to decrease alkalinity (left over alkalinity is RA). And result of that reaction would be part of the reason why calculators have diff. pH result.

I assume that mash temperature is also important especially if water is low in minerals, since phytase breaks down phytin at 86-126F and usual mash temp. today is between 140 and 160F.
According to that, if we use low mineral water (eg. RO with little salts), decreasing pH would benefit from acid rest since there is lack of Ca and Mg.

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Old 08-15-2012, 10:14 PM   #6
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The phytin reaction does release appreciable acid but 1) the water must be hard 2)the phytase must still be active i.e. the grains must be fairly low in color as you have noted. The difficulty the calculators run into is that prediction of the pH drop caused by certain concentration of calcium is based on an observation by Paul Kolbach back in 1951 and was actually for the pH drop in knockout wort - not mash. Again it's a question of applying a single observation to every situation.

The idea behind an acid rest is not so much to give time for the phytin reaction to take place as it is, at least in my understanding, to given lactobacilli an opportunity to get going and produce some lactic acid.

In modern brewing we usually don't rely on either the phytin reaction or lactobacilli - we just use sauermalz or lactic acid to set mash pH where we want it.

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Old 08-23-2012, 01:54 AM   #7
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For my last brew, I used both. Brun predicted 5.4,while ez predicted 5.5. My mash ended up about 5.45.



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