High FG / Low Attenuation across 3 different beers

Question

High FG / Low Attenuation across 3 different beers

Chris Dargis

2015年11月12日 00:22

I have brewed 3 all-grain batches now that have a high final gravity:

Imperial IPA: Target OG - 1.079, Target FG - 1.011, Actual OG - 1.070, Actual FG - 1.020, Yeast - US-05. Common attenuation range seems to be 73% - 78%. Apparent Attenuation: 70%

American Pale Wheat Ale: Target OG - 1.064, Target FG - 1.018, Actual OG - 1.054, Actual FG - 1.022, Yeast - White Labs WLP051. Advertised attenuation range: 75% - 80% Apparent Attenuation: 58%

Belgian IPA: Target OG - 1.060, Target FG - 1.014, Actual OG - 1.061, Actual FG - 1.027, Yeast - White Labs WLP500. Advertised attenuation range: 70% - 75% . Apparent Attenuation: 54%

I brew with Chicago water which has a high ph (around 8), have done 60 minute mashes at about 152 degrees. Originally I was having trouble hitting my OG, but I figured it out and pretty much nailed it on my third brew. But now after fermenting the third beer for 6 weeks, the FG has been stagnant for the latter 2 weeks at 1.027. I just bottled it and am certainly looking forward to trying it, but the FG was way off (13 points, where the first was 9 and the second was only 4). Every time, I aerated my wort and used a yeast starter. Thus I really doubt yeast health is an issue but of course I could be wrong. The Belgian IPA stopped at week 3 at about 1.030, so I added about 6 oz of corn sugar to try and get it going again. The yeast attacked it once I dropped it in, but the FG didn't come down much further. The temperature for each of these was around 65 degrees +- 3. I brought my Belgian IPA into a warmer room so it could stay at a steady 68 after the third week (also when I added more sugar) and it still didn't come down. I have been doing the mash in my 15 gallon brew kettle. I suspect my wort isn't as fermentable as maybe it should be. But I don't know what I'm doing wrong.

My question(s) is this: Before moving forward with another brew, are there any recommendations anybody has to ensure I can get closer to my FG? Would a high ph affect FG in this way? Should I be using a cooler for the mash instead of my stainless kettle? Should I increase the mash time? I have heard the that optimal ph for mash is 5.2 and that the mash process will reach this ph eventually. Should I start the 60 minutes AFTER I reach a ph of 5.2?

EDIT

There was never a problem with attenuation or FG being off. If anything, my FG readings were below the target. I didn't realize there was a wort correction factor when using refractometers for FG readings.

Topic final-gravity high-gravity attenuation all-grain homebrew

Category Mac

brendo234 · Accepted Answer · 2015年11月12日 00:22

1

brendo234 answered at 2015年11月12日 00:22

I'd agree with some of the above answers:

Try a new thermometer
Try lowering your mash temperatures

Dusty · Accepted Answer · 2015年3月10日 00:42

It all comes down to mash temp. Lower mash temps(145-148) will yield more fermentable sugars. Down side is you lower your mash efficiency and need to compensate with more grain or adjuncts. But you will have a substantially dry beer. Even with a iipa you should be able to hit 1.01.

brewchez · Accepted Answer · 2014年10月6日 17:00

Water may be the problem, but I'd focus on some easier solutions first. Confirming mash temp with a second thermometer. Mashing a little thinner (1.5-1.75qt/lb)and cooler (145-149F). And I would strongly recommend repeating one of the same beers you've already made so you can compare the end result with a prior result. THIS IS VITAL otherwise you really compound the ability to figure out what the problem is.

If you want to go down the water chemistry route I'd buy some cheap pH strips initially. Test the water pH and the mash pH and see where you are at. If you are in the 5.0-5.4 ballpark then your FG issues are more likely related to recipe or fermentation.

Lastly, at the end of your next test batch grab a quart of wort an do a forced fermentation test. Put that sterile quart of wort in a two quart sanitized jar. Add half a pack of US05 dry yeast (rehydrated) and let it ferment in warm place (80F). Shake it periodically to make sure they yeast don't settle out to soon. After a week check its SG, if the FG is where you wanted it to be, then you have a fermentation/yeast management issue with your beer.

Good luck

Daniel · Accepted Answer · 2014年8月1日 21:41

If your pH is that high in your water you'll want to lower it. pH that high will stop conversion/make it take longer. Look at using salts to add base to the water, also make sur eyou are using campden tablets to remove the chlorine and chloramine from your tap water if that what you brew with, yeast hate it.

jalynn2 · Accepted Answer · 2014年4月30日 17:48

I would focus on the yeast. How old were the yeast packs? Viability and cell count starts to drop off after just a few weeks. How big was the starter and what was the O.G.? Did you use a stir plate? There is a yeast calculator at Mr. Malty that I have found to be helpful. A stir plate helps quite a bit too. Make sure the temperature of your starter is near to the temperature you are planning to ferment at.

Graham · Accepted Answer · 2014年4月29日 19:05

I'd suspect either a faulty thermometer that's reading deceptively low is to blame, or perhaps your mash water chemistry is really off and you aren't getting full conversion.

For the former, check your thermometer in crushed ice-water to ensure that its reading 32F, and in boiling water to ensure its 212F. Don't be shocked if you can't get it to read 212F in boiling water, being off by a few degrees is fine. Also, if you've got another thermometer lying around, use both simultaneously in the mash and see if there's a difference in the readings.

Optimal mash pH is supposedly 5.2 (at mash temps), and I do believe that if you deviate from that drastically, you can impact your conversion, along with your efficiency. I'd suggest using all Reverse Osmosis water and following a basic water treatment plan, like Gordon Strong's, which simplifies the science a considerable bit.

Finally, make sure you're aerating enough. I've had a couple of high-FG brews lately and I think its a sign that I need to invest in an oxygen setup, but that might be overkill.

High FG / Low Attenuation across 3 different beers

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