Mash pH and final gravity

[klnosaj]

My final gravity is almost always high. I figured out how to ramp up my efficiency, but I can only rarely get beers to ferment out all the way. I'm usually about two points high, though sometimes three or four. I just ordered a pH meter after spending the bulk of the afternoon reading about brew water. I know that the pH of my tap water is quite high (8.8-9.2). Ceteris parabis, is my failure to account for this a reasonable explanation for higher than expected FG?

 

[Stauffbier]

Your problems could come from a number of things like;
-mash temps
-aeration methods
-proper yeast pitching rates
-yeast strain
-etc..

I would think water pH is going to have more of an effect on your starch conversion, and if you're hitting your expected OG and/or efficiency then pH might be fine. You need to check your pH during the mash to see where it's at..

 

[klnosaj]

Your problems could come from a number of things like;
-mash temps
-aeration methods
-proper yeast pitching rates
-yeast strain
-etc..

I would think water pH is going to have more of an effect on your starch conversion, and if you're hitting your expected OG and/or efficiency then pH might be fine. You need to check your pH during the mash to see where it's at..

As I said in my original post, I want to know if, controlling for these other issues, mash pH affects final gravity.

 

[ajdelange]

Mash pH has an effect on everything which is why it is so important to controll it. However water pH has little effect on mash pH. What does is alkalinity. It is usual, however, to find hefty alkalinity where mash pH is high but it doesn't have to be that way. For example if I add half a milliequivalent of lye to a liter of DI water it's pH will be 9.7 but its alaklinity will only be 25.

 

[Biobrewer]

As I said in my original post, I want to know if, controlling for these other issues, mash pH affects final gravity.

The short answer is not directly. However, your mash pH is going to have a large effect on your efficiency and your OG. If you are hitting OG, and your FG is high, it is likely NOT related to mash pH. It may be more of a function of mash temperature, fermentation temperature, and yeast choice.

Also, something important to consider is that you will not always hit your exact FG, and often times you may be a couple points high or low. It is EXTREMELY RARE to hit your exact FG, even if you did hit your OG.

If your thermometer is a degree or two low in your mash, you could be mashing higher than you think, resulting in slightly less fermentable wort (higher alpha-amylase activity, less beta-amylase activity) and a slightly higher FG.

Yeast vitality is also crucial in the FG of a beer. One pack of yeast may have lower vitality than another, which may also raise the FG a point or two.

I wouldn't be overly concerned with a point or two high in your FG. Like I said, it is very rare to hit it exactly. If the apparent attenuation of your yeast is within the range reported by the manufacturer, you are fine. Have you calculated your AA? If not, you should, and then compare to what the yeast manufacturer reports.

http://pint.com.au/calculators/alcohol/

This tool works well for calculating AA. Good luck!

 

[klnosaj]

Mash pH has an effect on everything which is why it is so important to controll it. However water pH has little effect on mash pH. What does is alkalinity. It is usual, however, to find hefty alkalinity where mash pH is high but it doesn't have to be that way. For example if I add half a milliequivalent of lye to a liter of DI water it's pH will be 9.7 but its alaklinity will only be 25.

I'm desperately trying to get my head around all of this. When I started brewing I likened it to cooking. Turns out it's more akin to baking. There's a reason I always preferred cooking to baking. I tend towards the arts over the sciences. But Lord am I trying! Helpers like you are indispensable.

The short answer is not directly. However, your mash pH is going to have a large effect on your efficiency and your OG. If you are hitting OG, and your FG is high, it is likely NOT related to mash pH. It may be more of a function of mash temperature, fermentation temperature, and yeast choice.

Also, something important to consider is that you will not always hit your exact FG, and often times you may be a couple points high or low. It is EXTREMELY RARE to hit your exact FG, even if you did hit your OG.

If your thermometer is a degree or two low in your mash, you could be mashing higher than you think, resulting in slightly less fermentable wort (higher alpha-amylase activity, less beta-amylase activity) and a slightly higher FG.

Yeast vitality is also crucial in the FG of a beer. One pack of yeast may have lower vitality than another, which may also raise the FG a point or two.

I wouldn't be overly concerned with a point or two high in your FG. Like I said, it is very rare to hit it exactly. If the apparent attenuation of your yeast is within the range reported by the manufacturer, you are fine. Have you calculated your AA? If not, you should, and then compare to what the yeast manufacturer reports.

http://pint.com.au/calculators/alcohol/

This tool works well for calculating AA. Good luck!

Thanks for that recommend. I've added it to my bookmarks. Turns out my Apparent attenuation was right on. I think perhaps BeerSmith 2.0 has misaligned my expectations. I hadn't thought of that but back checking a lot of numbers against the calculator confirms that I have been getting expected attenuation, if usually on the low side. That makes me feel better, for sure.

After too long mucking around in the quicksand of imprecision I think I finally have my numbers dialed in insofar as I have all the good testing equipment (refractometer, thermapen, graduated kettles, etc) and I always make yeast starters according to Mr.Malty's recommendation. I rarely mash at higher than 150 and tend to ferment towards the low end of acceptable ranges. I primary for two weeks, minimum and usually secondary for another 7-10 days. So all-in-all maybe you're right and I simply need to adjust my expectations.

Nevertheless, I ordered a pH meter yesterday and am on my way to the LHBS (Oak Barrel--is that your LHBS too?) for some acidulated malt and some calcium chloride. I also got a number for a guy at EBMUD (my water utility) so that I can track down some decent data on my water. Wish me luck....

 

[fpweeks]

I would double check your pH out if the tap. I would be surprised if a municipal water supply had a pH of 9.

 

[Stauffbier]

I would double check your pH out if the tap. I would be surprised if a municipal water supply had a pH of 9.

Yeah I agree! Mine is super high, and it's only 7.7!

 

[klnosaj]

I would double check your pH out if the tap. I would be surprised if a municipal water supply had a pH of 9.

Yeah I agree! Mine is super high, and it's only 7.7!

I spoke to one of the engineers at EBMUD today (a super cool guy...I was truly impressed by his willingness to take time out of a busy day to help me with my questions) and he said that the high pH is mostly a function of California law mandating high pH in order to protect the pipes. In a drought state like ours I guess we can't afford even the smallest amount of corrosion. It came in at 9.1 today and the range for the last year (8.9-9.4) is higher than it was for the year before (8.8-9.2). Our water here is delicious. But it's a little weird in that it has high pH but low alkalinity. After following the Primer I matched Pilzn water almost exactly. We'll see how it turns out for the Kolsch I brewed today.