Water Chemistry driving me loco....

[Loco_ola]

Hi, If i plug my water details into beersmith and use their mash ph calculator its been too low each time.

Ive got got a KH test kit and my local water report and put together this profile:

To get a mash pH of 5.5 in Beersmith it says to add around 5ml 75% Phosphoric to the strike water.

Brew n water says my alkalinity is 137.

If i try to remember some kind of Chemistry for this and I want to brew a pale ale, I'm aiming to get this to about 20. So

milliliters (ml) x normality (N) = ml x N
ml x N = millieqivalents
mg/equivalent weight = milliequivalents

Equivalent weight of CaC03 is 50
75% Phosphoric solution is 33.3 normal

So to reduce to 20 (so we remove 117 of CaCO3)
117 mg CaCO3 / 50 = 2.34 miliequivalents / litre
2.34 /33.3 = 0.07 ml per litre

This would give me on 21 litres of my water 21 * 0.07 ml = 1.47 ml total.

Am I totally wrong or going mad? Thanks so much for your help./

 

[Argentum]

Phosphoric acid technically has 3 x H+ ions (protons) which it can liberate, but it is classified as a relatively weak acid for which the pka dissociation constants for the last two protons have high pH associated values that are out of the range of typical mashing pH's. It is about 99.954% dissociated for the first proton at pH 5.5, and about 1.91% dissociated for the second, and there is effectively zip dissociation for the third. It therefore exhibits only about 1.9% more acidity than if treated as if it was monoprotic. At 75% concentration its effective mEq/mL of H+ (protons) at pH 5.5 is ~12.31.

117 mg/L alkalinity/50.04345 = 2.338 mEq/L alkalinity to be removed

2.338/12.31 = 0.19 mL of 75% phosphoric acid required per liter.

21 Liters * 0.19 = 4 mL of 75% phosphoric acid

But the alkalinity itself is not fully dissociated at pH 5.5 either, so in the end to get the water to pH 5.5 requires about 0.87 times 4 mL = 3.5 mL (or to get to pH 5.4 this factor is about 0.90)

Lastly, this 3.5 mL of acid is only addressing the alkalinity of the water. Then on top of this the grist has to be considered. Grist can be either acidic or effectively basic with respect to mash pH. It depends upon the malt constituents of the grist.

 

[strange-steve]

I used a different method of calculation but came to a very similar answer to @Argentum. Using stoichiometry (I'm not an expert on this by any stretch so this may not be a correct way to calculate this) I got the following:

H3PO3 + 3NaHCO3 = Na3PO3 + 3H2O + 3CO2

1 mol phosphoric acid reacts with 3 mol sodium bicarbonate

Converting to mass gives:
81.9g phosphoric acid reacts with 252g (3 x 84) sodium bicarbonate

Note that the sodium can be ignored for our purposes, so subtracting that from the mass means:
81.9g phosphoric acid reacts with 183g bicarbonate

Converting this to ml and accounting for dilution for 75% phosphoric acid gives:
1ml 75% phosphoric acid reacts with 889mg bicarbonate

Converting this to ppm alkalinity gives:
0.1ml/l phosphoric acid removes 73ppm alkalinity

Or

0.014ml/l per 10ppm alkalinity

So for your example above, you want to reduce alkalinity by 117ppm in 21L of water:
0.014 x 11.7 x 21 = 3.43ml acid

 

[strange-steve]

Rather than relying on estimates and calculations and since you have the KH test kit, my advice would be to test the alkalinity reduction yourself.

Take a known quantity of water, measure the alkalinity, add a known amount of acid, retest the alkalinity.

 

[Loco_ola]

Thanks so much guys that really helps! Great idea to use the test kit to check results.

Just a couple of other questions now, firstly how long does the complete reaction take after adding the acid and stiring, is it instant or should I wait some time before taking the reading?

The second is based upon my salt additions, which now bring the residual alkalinity down to 25.33 - do i actually need to add any acid at all?

Thanks again, really appreciate the help with this.

 

[Argentum]

I take mash pH readings no sooner than 30 minutes into the mash. If you are adding acid to water only, then by the time the acid and water are well and uniformly mixed it should be ready for a pH check.

 

[Loco_ola]

I take mash pH readings no sooner than 30 minutes into the mash.

Sorry, I meant how long before running the test for KH after adding the phosphoric acid to water. How long does that reaction take?

 

[Argentum]

I was amending my post above as you were typing. Answer is above.

 

[strange-steve]

The reaction will be pretty quick, just make sure to give it a really good stir. A few minutes should be plenty of time.

Secondly, I would suggest ignoring residual alkalinity. It's a different method for predicting mash pH, but targeting a specific water alkalinity value, which is what you're doing, is a simpler and equally effective way of doing it.

 

[Loco_ola]

The reaction will be pretty quick, just make sure to give it a really good stir. A few minutes should be plenty of time.

Secondly, I would suggest ignoring residual alkalinity. It's a different method for predicting mash pH, but targeting a specific water alkalinity value, which is what you're doing, is a simpler and equally effective way of doing it.

Cool, so I should add acid then check hardness. Then add salts to match my profile?

 

[strange-steve]

Cool, so I should add acid then check hardness. Then add salts to match my profile?

Yes. On a side note, is this for a NEIPA?

 

[Loco_ola]

Awesome thanks. I’ll prepare water tonight or in the morning.

Yeah sent the water section for a NE IPA recipe in the screenshot of my salts, I’ve got it dry hopping now.

However the removal of alkalinity to a level of 20 was in reference to a blonde ale I’m about to make.

 

[Loco_ola]

This is the suggested additions for the blonde... amends welcome! (notice I dropped the sodium content of the water. I suspect it's even lower than 15ppm but its not in any reports (I'm in the Alps)

So based on the calculation
0.014 x 11.7 x Water Volume =ml acid

In addition to the salts above I'm going to be adding.

20 litres of strike water = 0.014 x 11.7 x 20 = 3.276ml acid
9.74 litres of sparge water = 0.014 x 11.7 x 9.74 = 1.6ml acid

Presumably I check mash pH 30 mins in and add additional acid if required?

 

[Argentum]

The mash is effectively over at 30 minutes (or mostly so) and that does not leave time to add acid, plus it will not alter the past. The next juncture for acid addition is just prior to boil, where you want to take the wort down to pH 5.2 as measured at room temperature before proceeding to boil. 5.0 to 5.2 pH is acceptable leading into the boil, but try to favor 5.2.

 

[Drunkula]

The mash is effectively over at 30 minutes (or mostly so)

I was reading an old (1982) wine and beer book last night because I thought I might do the beer recipe for each month for a laugh. The mash times are four hours! And most recipes have loads of syrup or sugar and some delightful sexism.

 

[Loco_ola]

The mash is effectively over at 30 minutes (or mostly so) and that does not leave time to add acid, plus it will not alter the past. The next juncture for acid addition is just prior to boil, where you want to take the wort down to pH 5.2 as measured at room temperature before proceeding to boil. 5.0 to 5.2 pH is acceptable leading into the boil, but try to favor 5.2.

Ahh gotcha, mis-understood what you said earlier. So take the reading at the start of the mash and adjust if necessary then?

And then another check after mash out and adjust again if required.

Sorry if these are stupid questions!

 

[Argentum]

Ahh gotcha, mis-understood what you said earlier. So take the reading at the start of the mash and adjust if necessary then?

And then another check after mash out and adjust again if required.

Sorry if these are stupid questions!

A much better approach is to nominally adjust to ballpark hit a targeted mash pH pre dough in.

 

[Loco_ola]

A much better approach is to nominally adjust to ballpark hit a targeted mash pH pre dough in.

Cool, I thought so - I intended to do that as above in my post 13. I meant purely if it's way off the mark. Although I guess making any adjustments to pH at mash temps is just too much hassle anyway.

 

[Argentum]

Cool, I thought so - I intended to do that as above in my post 13. I meant purely if it's way off the mark. Although I guess making any adjustments to pH at mash temps is just too much hassle anyway.

I'm coming to understand that one last acid adjustment which is to be made immediately pre-boil and which is targeted to to hit ~5.2 pH (5.0 to 5.2) as measured at room temperature is not something that should be ignored. It may be as much or more important than adjusting pH within the mash (which may only be necessary for the case of mashing at 5.9 or above pH, or for bringing up what might otherwise be a mash at below 5.2 pH). And for ~30 years I didn't even know about, or ever even consider this option.

 

[peebee]

Hi, If i plug my water details into beersmith and use their mash ph calculator its been too low each time. ...

The water treatment stuff in Beersmith is pretty new. I've tried using it and come to the conclusion it needs a bit more time. For me it is always coming out way too high. So I continued using Bru'n Water.

Funny enough I've spent a lot of time recently in a thread on this water malarkey on another forum. I'm currently looking at an alternative to Bru'n Water and … hang on …

(Argentum=Silver, location N/E Ohio, signature 'Mash Made Ea …' ).

@Argentum, it's you isn't it!