Acidification using phosphoric acid?

I recently got around to picking up a pH meter and a lomotte water test kit. It's all new so I'm planning on running the tests again before I trust the results but this is what I'm working with currently.

My water pH 7.97

100 PPM Total hardness as CaCO3
50 PPM Calcium hardness
12 PPM Magnesium
50 PPM Chloride
0 PPM Sulfate
130 PPM total Alkalinity
46 PPM Sodium

I have been doing some research on water but I'm very new to water adjustments.

I've always brewed using 5.2 or adding acid malt to the grist.

I've read that the mash pH is acceptable if it is in the range of 5.2 to 6. So I've been looking at a couple of things.

I'm looking at standardizing my grist composition mashing mostly base malt and top mashing the rest of the grist during a 15-20 minute recirc, measuring the pH once all of the wort is collected and using 10% phosphoric acid to lower the wort to 5.2.

I know the grist composition will have an effect on the kettle pH. My current plan is to dose in small amounts until I reach the desired pH. I have been working with a few different spreadsheets but the are all excel and I'm running them on apple numbers and the two don't seem to work well together.

Let's assume a low SRM beer what amount of phosphoric should I start with per gallon of wort?

killian said:

My water pH 7.97

100 PPM Total hardness as CaCO3
50 PPM Calcium hardness
12 PPM Magnesium

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100 ppm as CaCO3 hardness is 2 mEq/L
50 ppm as CaCO3 calcium hardness is 1 mEq/L
12 mg/L as the metal is 1 mEq/L
Thus we must assume that the hardnesses are, respectively, 50 and 50 necessary to sum to 100 and that the ion concentrations are Ca++: 20 mg/L (1 mEq) and Mg++: 12 Mg/L, both as the ion.

killian said:

130 PPM total Alkalinity

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This is the animal you need to deal with.

killian said:

46 PPM Sodium

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That's getting to be quite a bit but you can probably live with it.

killian said:

I've always brewed using 5.2 or adding acid malt to the grist.

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And you know that the former is not effective at adjusting mash pH but the latter is.

killian said:

I've read that the mash pH is acceptable if it is in the range of 5.2 to 6.

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There is discussion of this in a current thread. The consensus seems to be that mash pH should be kept below 5.5 (at room temperature) but that up to 5.6 is OK in many cases.

killian said:

I'm looking at standardizing my grist composition mashing mostly base malt and top mashing the rest of the grist during a 15-20 minute recirc, measuring the pH once all of the wort is collected and using 10% phosphoric acid to lower the wort to 5.2.

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5.2 (or a bit lower) is desirable for knockout wort pH but your first job is to get the mash pH into the 5.4 - 5.6 region. If you do that knockout pH will usually be close to the desired value.

killian said:

I know the grist composition will have an effect on the kettle pH. My current plan is to dose in small amounts until I reach the desired pH.

Click to expand...

Unsurprisingly enough the respective alkalinities of the grains and the water determine mash pH. You must allow for both. One technique is to 0 the alkalinity of the water. This can be done by adding phosphoric acid (or any other reasonable food grade acid) to the volume of water to be used until the desired mash pH is reached. As the 10% phosphoric acid sold by LHBS's is about 1 N the amount required will be a bit less than the number of liters treated times the alkalinity divided by 50. That leaves the grains to deal with. Base malts require approximately 40 mEq of acid per kg per unit pH shift from the DI water mash pH. Thus if you have a base malt with DI pH of 5.8 and you want to mash it at 5.4 you are going to need about (5.8 - 5.4)*40 = 16 mEq (16 mL 10% phosphoric) for each kg of that malt you use. As there are quite a few approximations here (and some of the spreadsheets get into even wilder ones) it is best to make a test mash and scale the results to the full brew length.

killian said:

I have been working with a few different spreadsheets but the are all excel and I'm running them on apple numbers and the two don't seem to work well together.

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That Bill Gates got to be the richest man in the US by selling the merde he does is an annoyance for sure but nevertheless Excel (which could actually be a very good product on Apple machines if they ported it correctly) is quite useable on Apple machines. The trick is to select the entire spreadsheet and then change the font. You can do this with any of the Excel spreadsheets except Bru'n water in which the cells are locked.

killian said:

Let's assume a low SRM beer what amount of phosphoric should I start with per gallon of wort?

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SRM has little to do with it. Assuming that you want to control mash pH to 5.4 and that you are mashing each pound of grist with 1.2 quarts of the water as specified and that the grist is straight Crisp Maris Otter you would need 7.86 mEq of acid per pound of malt in the grist which, as 10% phosphoric acid, would be about 7.2 mL.

I have just started reading the Brewers publications water book (and actually just read your forward) pretty awesome that you'd take the time to look at my post, thanks!

I was using palmers calculator that has selectable menu options that I can't select/change; I've switched to kaisers sheet and I think I'm back on track.

I wish I had paid more attention in chemistry in school. I have so many questions. If you can, please bear with me as I work some issues out...

Does phosphoric acid precipitate calcium? I know I need a minimum of 50 PPM Calcium and my water (current results) is right at 50 PPM without any adjustment.

I thought the SRM was an issue that's why I was looking at top mashing so I could standardize my mash profile.

Everything is pointing toward adjusting mash pH, what effects are there if the mash pH is above or below the recommended range? I'm guessing it has to do with the enzyme activity but as noted before I was brewing with 5.2 which wouldn't have been effective for adjusting pH and I was still hitting a predictable gravity.

killian said:

Does phosphoric acid precipitate calcium?

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It can but the calcium concentration needs to be pretty high. I put together some curves for John and they are in the back of the book.

killian said:

I know I need a minimum of 50 PPM Calcium and my water (current results) is right at 50 PPM without any adjustment.

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Calcium confers many benefits but lots of good beers are made with quite a bit less than 50 ppm.

killian said:

I thought the SRM was an issue that's why I was looking at top mashing so I could standardize my mash profile.

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This idea stems from the fact that historically dark beers were brewed where the water was alkaline. There is a correlation between beer color and alkalinity but it is a loose one.

killian said:

Everything is pointing toward adjusting mash pH, what effects are there if the mash pH is above or below the recommended range?

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There is a current thread which nicely summarizes the thinking on that.

killian said:

I'm guessing it has to do with the enzyme activity but as noted before I was brewing with 5.2 which wouldn't have been effective for adjusting pH and I was still hitting a predictable gravity.

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It is enzyme activity for sure but it is not necessarily the amylases but rather the enzymes that modulate malt flavors. Beers just taste better if mashed at pH < 5.5.