Has mash ph been an improvement for you?

[MHB]

So a bit more soluble than AgCl which sort of defines Insoluble.

 

[drsmurto]

Why do you think your mash pH needs correcting?

 

[Lyrebird_Cycles]

The one that is revelant to brewing is calcium hydrogen orthophosphate, it has a Ksp of 1 x 10^-7.

So a bit more soluble than AgCl which sort of defines Insoluble.

EDIT: From info below it looks like I was wrong about calcium hydrogen orthophosphate being the relevant model, it is hydroxyapatite. Solubility of hydroxyapatite is much more complex so I've redacted this post.

 

[mtb]

Why do you think your mash pH needs correcting?

It's a justifiable assumption given the average water profile in Aus, and the target profiles advertised by Bru'n Water and the like.

ed: I'm referring to the target profile for the common brewing recipes, ie pale ales and lagers. Capital cities at least require some form of modification to hit the optimal pH without using darker grains in a proportion higher than the recipe calls for.

 

[drsmurto]

Yes. Measure pH. If it's out of whack then decide what to do about it. Assuming your mash pH is out of whack and attempting to adjust is arse about, particularly if you don't measure pH after any adjustments.

 

[mtb]

I agree completely, which is why I invested in a pH meter.. but is your local water profile report not enough to know the composition of water from your tap?

I bought a pH meter to double-check the readings post alteration, but I trusted the water profile to know what water I was starting with. Maybe I shouldn't..

 

[drsmurto]

Not sure what your water profile has do to with mash pH.

Regardless of what water I have used for brewing, I've never measured a mash pH out of the desired range. I've even used an IPA as the water to brew with (beer, made from beer a la the Carlton Draught ad) and still got a mash pH bang on. Naturally occurring buffers FTW.

It's good you're actually measuring mash pH, far too many don't but insist of attempting to change mash pH with various means. I'm assuming they rely on the same level of assumptions for the mash temperature. It's the vibe.

Ignore this grumpy scientist, I probably just need to pour myself a beer and relax.

 

[mtb]

Nah you're alright drsmurto, I've had a few already which means I've probably not interpreted your response properly.

Let's all have some beers!

 

[peteru]

If you are taking pH readings as you go and the pH appears too high, at which stage would you contemplate adding lactic? After 2 minutes, 10, 20, half an hour into the mash?

 

[timmi9191]

Isnt the ca precipitation following acidification with phosphoric dependant upon ca saturation? Ie at ph 5.5 16mg/l ca will not be effected.

Also if phosphoric is used to adjust mash ph, as opposed to strike water ph, wouldnt the issue of ca precipitation be redundant?

 

[Lyrebird_Cycles]

Isnt the ca precipitation following acidification with phosphoric dependant upon ca saturation? Ie at ph 5.5 16mg/l ca will not be effected.

EDIT: See above

 

[Jack of all biers]

If you are taking pH readings as you go and the pH appears too high, at which stage would you contemplate adding lactic? After 2 minutes, 10, 20, half an hour into the mash?

The earlier the better*, as this allows the enzymes more time in the preferred pH range of 5.2-5.6. Thereby allowing them more time to fully convert the starches to sugars. It also allows less time for tannin extraction if your measured mash is pH 5.8 or higher

*This assumes that the measured mash pH is out of the above range to begin with. If it is just to adjust to within that range (ie from 5.5 to 5.3), well, I'd suggest that you're worrying over a minor thing and it doesn't matter. If it is to hit a certain pH goal for the finished beer, then I'd suggest that it won't matter (as long as you are within the preferred mash pH range) and you can acidify in the kettle or post boil.

 

[Lyrebird_Cycles]

Regardless of what water I have used for brewing, I've never measured a mash pH out of the desired range.

I have definitely recorded mash pH outside my desired range and have been able to bring it back in range by changing mash salts.

I'm confident my pH measurements are OK, I've been doing this a while.

 

[manticle]

I've also found mash pH (mostly paler) outside range and calcium in waters I've used is always low.

That said - I agree with DS's point - measure first, action afterwards based on results.

 

[Jack of all biers]

It is dependent on Ca concentration (not saturation), as explained in my post above.

I'm not sure what you are asking in the second sentence so I can't answer.

I think what @timmi9191 is referring to is about calcium carbonate and calcium phosphate (and particularly hydroxyl apatite) being less saturated at lower pH. This is explained in short on page 115 & 116 or more thoroughly on page 253 "Example 3 - Determining calcium loss from Phosphoric acid additions" - Appendix B in the book 'Water - A comprehensive Guide for Brewers' Palmer/Kaminski, Brewers Publications 2013. Appendix B was contributed by A.J. deLange and he has used the term calcium saturation, when concentration may be more appropriate.


For those that don't have the book , but are interested I summarise below; (for about $25 delivered to your door, just buy it)

In short deLange states that apatite precipitation as a function of phosphoric acid addition can't be predicted as the mechanisms are hard to model. He further states that the saturation levels of calcium that can be tolerated before the onset of precipitation as a function of pH can be calculated. He says that the saturation limit is conveyed by "Sat. Ca+2; H2PO4; pH(X).

DeLange provides charts which show the remaining alkalinity of water after acidification and saturating (WRT Apatite, pKs=114) calcium concentration if brought to pH with phosphoric acid. These are done with differing Total Alkalinity concentrations (as CaCO3) [at 50, 100, 150 & 200ppm] and source water pH levels that have been acidified with phosphoric acid to pH 5.2, 5.5, 5.75 & 6. They show the respective saturation levels and calcium concentrations.

DeLange states that "the saturation limit for calcium increases the more you acidify", however, "the calcium saturation limit decrease with increasing total alkalinity level". For example;

• for a source water with 16mg/L Ca, 50ppm CaCO3, a pH of 7.5 and using phosphoric acid to reduce it to pH of 6 the calcium saturation limit is about 40mg/L. Meaning concentrations of calcium above 40mg/L will likely precipitate out as apatite, but concentrations of calcium below won't. Not great right, because if you added 150mg/L Ca to the original 16mg/L Ca it would be reduced to 40mg/L or just under.
• That same pH 7.5 source water acidified to pH 5.5 by phosphoric acid has a calcium saturation limit is of 400mg/L, meaning that one would need to up the Ca concentration to be 400mg/L or higher to start losing Ca to precipitation into apatite.

However, with increasing total alkalinity, for example, a source water with;

• 100ppm CaCO3, 7.5 pH then acidified to pH 6 the calcium saturation limit is just over 20mg/L Ca and acidified to pH 5.5 it is around 180mg/L Ca.
• 150ppm CaCO3, 7.5 pH then acidified to pH 6 the calcium saturation limit is about 20mg/L Ca and acidified to pH 5.5 is about 110mg/L Ca.
• 200ppm CaCO3, 7.5 pH, then acidified to pH 6 has a calcium saturation limit of about 20mg/L Ca and acidification to pH 5.5 has a calcium saturation limit of about 80mg/L Ca.

If you add Ca salt additions above those 'Ca saturation limit' concentrations then you are as LC and MHB said 'making expensive silt'.

So in short, if you have higher Total Alkalinity water to begin with and need to move the water pH down with phosphoric acid then, you should ensure you know what you are doing or probably look elsewhere or add your Ca additions to the boil so as to not lose significant amounts.

My Adelaide tap water has total alkalinity of 44 mg/L CaCO3, so I add Ca salts to the mash and very occasionally acidified malt (lactic acid essentially) and acidify my sparge water with phosphoric acid (aiming for pH 5.4, but often going under that). But if I ever did need to add acid to the mash, due to being out of acidified malt, I would not hesitate as I know that the Ca levels wouldn't be precipitated out as apatite.

EDIT - It appears that there is an error in the text of the book that threw-out my reading of the lower numbers on the charts. I have changed these to reflect the values provided in the charts, ie 4mg/L was actually 40mg/L on the chart.

Also what I didn't cover in the above is that if you add your Ca salts to the mash and measure the mash pH to be 5.75, but want to acidify to 5.6 to 5.2, even with 200ppm CaCO3 water, your calcium saturation limit is very high (above 200mg/L Ca) so to use phosphoric to do so should not reduce the Ca concentrations through extra precipitation as apatite.

Also, deLange modelled his results with CaSO4, not CaCl. He states if the SO4-to-Cl ratio is less than 1:2 or no SO4 at all (in the source water or by additions) then cut the Ca saturation values in half.

 

[Doctormcbrewdle]

Yea, dude. A light pilsner vs. an imperial stout aint exactly gonna be close in ph.

 

[Doctormcbrewdle]

Well my new ph meter arrived in the mail yesterday. Calibrated it and reads 7 in tap water. Out if curiosity I tested an older IPA which reads 4.9ph. Not sure if beer ph changes much from mash but that's what I got anyway. It's a 7.5% abv so not going to be same as a pale ale perse'

 

[Lyrebird_Cycles]

Yes, beer should have a lower pH than the mash: pH generally falls by a bit more than 1 pH unit during fermentation, the actual change is dependent on wort composition, yeast strain and fermentation conditions.

That being said, 4.9 is very high for a finished beer, most beers will look soapy at that pH.

 

[Doctormcbrewdle]

Yes, beer should have a lower pH than the mash: pH generally falls by a bit more than 1 pH unit during fermentation, the actual change is dependent on wort composition, yeast strain and fermentation conditions.

That being said, 4.9 is very high for a finished beer, most beers will look soapy at that pH.

Thanks L

Well it certainly does look soapy. And taste it too. Although, my meter is cheap. It does, however measure 7 in tap water and line up at 7.2 with my test strips in the pool which are accurate (there's 5ph colours in 0.2 increments) I'd hate to see where my APA and pilsners are sitting.. Could this really be correct, or could it be my meter?

I added 10g calcium salts to that 23l batch too

Edit, it's my Meter. Just tried again with the pool test strips and it's almost a full point out.. off to Ebay as we speak

 

[Doctormcbrewdle]

Any suggestions for a new meter anyone?