I searched the questions and did not find an answer to my particular question. As the title says, my question is: What effect do water ions have on mash efficiency other than adjusting Ph?

Put another way, do ions like Calcium, sulfate, carbonate, magnesium, etc. have a direct impact on mash efficiency or is their role limited to adjusting Ph?

Back story: Brewed on Sunday for the first time with reverse osmosis water, which has virtually no water ions and a Ph of 7. I used a buffering solution to adjust Ph to 5.2, confirmed with a digital Ph meter. Other than that, I did not add back those ions until the boil phase. My efficiency was horrible. I think it was because I was also using new grain bags that were too tight, but I'm curious whether I should add the salts BEFORE the mash.

Thank you, Sean

  • I'm no expert but I did a bit of research into water salting recently and I never once read anything about efficiency. I tend to doubt it would be the cause of horrible efficiency. Is there something to lead you to believe it could be? BTW salts greatly effect the taste of the beer too, not just PH. Also I'm not knocking 5.2 buffer at all as I know very little about it but I will say that a lot of other people did when I brought it up myself. I'm sure it must have it's uses ... and fans ... but it's somewhat controversial it seems Commented Feb 6, 2017 at 22:20

3 Answers 3


IMHO it is the pH of the mash is the important thing. pH of the source water is not so important - as long as it is not ridiculously high of low.

Barley and wheat amylase enzymes work optimally in the presence of calcium ions, one could say they require calcium ions to function. So using totally de-ionised water for mashing/lautering/sparging is not an optimal procedure. Some calcium carbonate/sulphate/chloride must be added as appropriate for the mash pH.

Other ions generally have a varying but more negative effect on barley or wheat amylase activity. To quote an online source Zinc2+, Ammonium+ and Iron3+ ions are inhibitors of amylase.

IIRC Calcium ions aid flocculation and precipitation of protein and other high Molecular weight organics to produce a bright wort.


Water salts are not going to effect lautering efficiency to any large degree. Mash efficiency is a made up term that takes into account both lautering efficiency and conversion efficiency. It sounds to me like you have a lautering problem. If the grain bags are too tight you likely have some conversion efficiency as well if not all the grain is properly hydrated.

Water ions effect pH which does have a direct correlation to conversion efficiency. You do need some calcium to help drive good enzymatic conversion, of which 5.2 stabilizer does not provide. However, most malt on its own has enough Ca++ and Mg++ for conversion. We just need to add more to get to the optimal pH range when working with RO water.


Brad smith has a cast that covers the ions and importance. The interview is a bit awkward as the guy he's talking with knows water control and isn't a brewer but Brad walks him through each of the important parts and what it means to the brew. As for efficiency, I've seen mash temps play the largest role. As little as 5 °F can drastically change the gravity. Also tightly packed (thick) mash can lead to less fermentables than a thin mash


  • This is one of Brad's worst interviews. Its like he did no prep. The guest keeps saying he doesn't really now anything about brewing. He is just a water chemist. Yet Brad can't get off his own script of questions and keeps asking about mash chemistry. Not saying there isn't some decent info, but its tough to listen too.
    – brewchez
    Commented Feb 10, 2017 at 11:51

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