Using sparge water to adjust kettle pH.

[Queequeg]

So I am making a stout soon with a target mash pH of 5.6. I want to bring this down to a optimal kettle pH of 5.0-5.2.

Now I could do acid additions directly to the kettle though this is a big faff, drawing a litre, chilling and then making gradual additions before scaling up in the kettle. My brew day is long enough as is, so no thanks.

Instead is there anything wrong with adjusting the sparge pH to compensate.

Normally I will just ensure my sparge water is around 5.5 to avoid tannin extraction.

But is there anything wrong with say, adjusting it to the sparge pH to 4.6?

As a rule I use a mash volume/sparge ratio of 1:1. So ignoring any buffering capacity of the finished mash this would work out as a kettle pH of 5.1 ((5.6+4.6)/2).

Obvious this is an over simplification, but unless anyone knows of a kettle additions calculator...

Alternatively I could add PA at the end of the mash according to bru'n water to bring it down to 5.1 and then acidify the sparge to 5.1.

Can anyone see any issues with either approach? are there any problems with a low pH sparge? For those who adjust kettle pH how do you do it?

 

[mabrungard]

For the stouts and porters that I've made, I've always carried the slightly elevated mashing pH over into the kettle. While I haven't tried your approach, I'm concerned that the lower pH may make the roast character harsher in the beer. The 'optimal' kettle pH is typically a post-boil pH and its often applied to pale beers where crispness is enhanced by the slightly lower wort pH. That aspect is unneeded (possibly unwanted) in darker styles.

 

[Queequeg]

Well that makes things very easy indeed. Thanks Martin.

I want to start adjusting my kettle pH for my IPA/apa's too. Typically I mash at 5.2/5.3 for these styles. That being the case could I acidify my sparge Down to pH 5.0 to ensure a o.k kettle pH or might this cause unforseen problems.

 

[Gnomebrewer]

The pH scale is logarithmic, thus 5.1 is NOT halfway between 4.6 and 5.6 in terms of concentration of H+ ions. There's also the buffering capacity of each mixture to consider - in theory you could mix two solutions of equal volume, one at 4.6 and one at 5.6 and end up with a final solution of 4.7, or 5.5.

 

[Queequeg]

O.k, so it looks like plan A won't work. still is there any lower limit to sparge water pH.

There will be no harm in sparging with say pH 5.1 water? especially if I mash at 5.2/5.3.

My concern is if you sparge with 5.5-5.7 pH water it will for a low pH mash potentially raise it, if only by a small amount. If there is no disadvantage of sparging at target kettle pH then that would at least for pale beers seem the best practice.