Yes, it was calibrated directly before use. Intended pH was 5, measured pH at room temperature was 4.46.

Yep, in my opening post I mention that I was suspicious of the numbers before I was about to perform a mash so I did a mini mash to check, and found that I needed to almost halve the acid suggested by Brewers Friend, an amount which happened to almost exactly match what Bru'n Water suggested.

Yeah, dosing acid after packaging is a good and enlightening process, but it will of course not go back and alter the chemical processes which the beer, and before that wort, has undergone. It certainly is a complex topic, and one on which I am on the wrong side of the accepted norms, but I...

I don't suppose I will use the Brewers Friend calculator again in its current incarnation, so the only way I can give you any data will be to perform test mashes, which I am not particularly inclined to do again at the moment. I would have thought the discrepancy between the two calculators was...

Thanks for doing that, at least I know I'm not missing something obvious on the calculator. As for why I want it that low, there are lots of good chemical reasons to want to push the pH below the traditional range. Despite the commonly held beliefs there are few downsides to mashing low, and...

I can guarantee you that what I have put into both calculators is identical, and those are the outcomes. I have only used mash liquor with no sparge for the example, and I have the Brewers Friend calculator set to only acidify the mash water, and likewise in Bru'n Water. Anybody can feel free to...

I use Bru'n Water to compare, since I know that works consistently for me even if I target slightly unusual mash pH ranges (for which I have my reasons). I was hoping to only use Brewers Friend from now on, but unfortunately it just doesn't work, at least not in the cases I have looked at. Take...

I think it's ok if you only need to make small adjustments or adjustments with salts only, but the calculated acid additions when you want to deliberately target an unusually low mash pH (say a pH of 5 for a crisp pilsner when your base water alkalinity is around 150ppm as CaCO3) end up way off.

As the wordy title says the advanced water chemistry calculator is currently wildly inaccurate with its acid addition suggestions, a few weeks ago this nearly caused me to lose hours of work on a pilot batch had I not thought the numbers seemed off and done a mini-mash first to check. The...