Understanding my water report

[orlando]

I have water with similarly low alkalinity but I never try to increase alkalinity with stouts and other dark beers. What is likely to be wrong with these beers as a result?

Darker roast malts have an acidifying effect on the mash, alkalinity acts as a buffer, resisting a shift in pH, the higher your alkalinity the less acidification required, e.g. CRS or other acids. If your mash pH falls below 5.2 you run the risk of extracting harsh tannins from the malt making the beer more astringent, there can also be issues with attenuation. I've even tasted a slightly sour note, but Guinness make a virtue out of it so what do we know.

Correction: A mash pH closer to 6 extracts harsh tannins, apologies for misleading.

[Clibit]

I have very soft Manchester water. I either steep dark grains separately, or add them to the mash for the last 30 mins. Do these methods remove the need to add potassium bicarbonate to the mash?

[Aleman]

I suspect they do . . . certainly steeping separately does.

Adding for the last 30 minutes of a 90 minute mash, will favour alpha amylase activity to the detriment of beta amylase, but after 60 minutes the amount of beta amylase activity will be low anyway.

FWIW I did a RIS with a massive amount of dark malts and forgot the water treatment mash pH was 4.8 . . .Beer was excellent

[Clibit]

Thanks very much Aleman. I kind of figured that steeping would negate the need for potassium, and adding late to the mash might not.

I have also made dark beers with zero water treatment and they've been great, which does make you wonder....1

I also read an interview with a brewer from the Manchester Marble brewery in which he said they don't treat the water for dark beers, and add gypsum for pale beers. So I've always kept things very simple, experimented a bit.