Brewing a Dry Irish Stout, adjusted water to dublin profile, my mash ph is 5.8. Problem?
It could easily be a problem. 5.8 is higher than I prefer. 5.6 is the highest I recommend.
This is another example of using a historic profile and not understanding what those historic brewers did to brew with it.
Martin, funny you mention this because just the other day I told an individual I was brewing a saison and he asked me if I was using the water profile for Brussells, Belgium. He’s an extract brewer and I had to explain that those water profiles aren’t all that meets the eye, and although most water profiles helped establish certain beers brewed in certain areas there was still likely water manipulation.
Heck, Sam Adams as a brewery in Cincinnati, OH. Certainly Cincy and Boston don’t share the EXACT water profile! 
Brewcarp, you haven’t provide mutch info on what you did. it most likely is a problem, your efficency will suffer. i use some mineral additions to match my water to a profile i desire. then after mashing for 10 minutes i check my ph and use lactic acid to adjust. i use bru’n water spreadsheet for these calculations. See 2 posts above for link
Since posting this I have 1) enjoyed the stout very much, came out fine, 2) re-brewed and came out with a proper ph. I can only assume my first readings were wrong. The beer was fine and loved by all! In my re-brew I saved and soured about a quart of the first brew and added it to the boil of the second. Can’t wait to taste the difference, should make it more Guinness like, although the first was damn near perfect!
Angels 10, gremlins 0. How I love happy (hoppy?) endings!
Maybe, for the good of the order, you could plot on a graph how many times your mistakes end up with RDWHAHB. :cheers:
Brewcarp, you don’t mention where you are brewing at and what your water is like. (by the way, you don’t have to hide on the internet, most people couldn’t care less who any of us are)
To produce a 5.8 pH, the water would have to contain a fairly high bicarbonate content. So unless that is the case, there is a decent chance that the mash pH reading might have been off. The good thing is that at 5.8, that pH is not really high enough to create off flavors in your beer.
Enjoy!
