Attenuation sucks - must be the mash, but...

Sorry for the novel. I'm just giving every piece of info I can I think of so I can get some help.

I’m having 2 issues. I guess it’d be nice if one was the cause of the other, so I could fix everything with one fell swoop, but that may not be the case. I’m hoping some brains here can help.

The priority issue is my attenuation. I am ALWAYS stopping 4, 5, 6, even 7 points short of my target gravity. I’m using med-to-high attenuating liquid Wyeast yeasts, using a 1L starter on a stir plate for at least 24 hours, using a pinch of yeast nutrient for the starter, and adding a tsp of nutrient for the boil, using a siphon spray into my primary fermentor, and then shaking the ~5.2 gallons in the 6.5 gallon carboy (so there’s headroom for good splashing) for at least 2-3 minutes.

My grain bills are not particularly heavy on the unfermentables – they are almost always based off of some BYO recipe. Last one I did was a quasi-Guinness close: 7.5 lb Marris Otter, 0.5 lb flaked barley, 0.75 lb roasted barley, 2 oz chocolate. My OG was 1.043, right on target. I used Wyeast’s 1764-Pacman from Rogue (expected to get 72-78% attenuation), fermented perfectly @ 63 degrees with the airlock bubbling solidly for 3-4 days and then slowing down for the 5th, and STILL she’s all tuckered out at 1.016, only 63% attenuation.

Just racked last night and it’s a good beer, but noticeably sweet. I wanted a DRY stout, dang it!

Every beer I do is the same.

• Yeast count and health is fine.
• Recipe is fine.
• Fermentation is fine.
• Aside from getting an aeration stone, I really don’t think there’s anything more I can do for O2 levels.

So, I’m thinking the problem has to be in my pre-boil processes, right?

Which leads me to issue #2; controlling my mash-out temps.

MY MASH: I heat my strike water and mash in a 10-gallon stainless steel kettle with a false bottom that sits above 1.5 gallons of water. I always aim for strike water 11 degrees above my mash target (which, for the Dry stout, was 150), and after pouring in the grain and stirring a few minutes to break up clumps, my built-in dial thermometer and my handheld probe thermometer both tell me I’m within a degree of target. Happiness abounds.

Q#1: Regarding that 1.5 gallons of water under my false bottom. That’s a pretty heavy chuck of heat down there, which I can’t get to with my spoon when I stir in the grains. Is it possible that my temp readings are only telling me what’s happening at the top and middle of my mash, but nearer that false bottom where the water once was 161 degrees, the mash is really closer to 155 or higher? Does anybody else have a mash-tun like mine (bought from MoreBeer)? Should I be recirculating a few quarts and stirring before I wrap up the mash to let sit?

After mashing 60 min, I (attempt to) MASH OUT. I apply direct heat, and begin recirculating+stirring. I draw off a quart at a time, put it back in pouring it gently over the back of my metal spoon so as not to aerate, and stir the mash to try to disperse the heat. I do this about 5-6 times, watching my built-in dial thermometer. 15 min later or so, the thermometer tells me I’m just about @ 170. I shut off the heat, recirculate once or twice more and start my sparge. 5 minutes into the sparge, my dial thermometer starts wigging out, rapidly climbing higher and higher, soon telling me I’m up to 195! I get angry and call it a liar. About 10 minutes after that, it’s back down to 148, and slowly but steadily dropping down through the 140’s (despite the fact that I’m using sparge water @ about 180 degrees).

So, I’ve just about had it with this mash-out process which seems like it is probably doing more bad than good. Next time I’m going to try to mash out by adding a quantity of boiling water.

Q#2: In calculating how much water I need, BeerSmith asks me how much grain I’ve got and how much water I’ve got. Of course it’s referring to the water I’m using to mash (1.3 q/lb), but should I also consider the 1.5 gallons of water below the false bottom in this calculation? It seems I should since it must have an effect on the total heat present. I’m wondering how much that 1.5 gallons is to blame for many of my issues.

Q#3. Is there a possibility that these wacky temps I’m getting during ‘mash out’ are having an effect on conversion or are otherwise the cause of my miserable attenuation?

I don't think your mash-out is causing your frustrations, but it may be a clue. By mash-out, your enzymes have already done their work and your starches are already converted as good as they are gonna be for your mash temp. Higher mash-out temps will pull bitterness from the grain hulls but that's about it. (colder mash-out temps may leave behind some sugars are all btw)

BUT.... your "wildly swinging mash-out temps" may be a hint. That instability in temps leads me to believe that your mash temps are either not where you think it is OR it is not even thru the grain bed. ie: it's at 150 where your thermometer is mounted but much higher somewhere else in your grain.

Maybe? That would be my best guess.

Also didn't notice if you have tried different yeasts in your testing?

Perhaps my mash temp readings aren't consistent throughout, but if my strike water readings ARE accurate... then my mash temps can't be that far off. If I'm adding room-temp grain to 161 degree water, I HAVE to land somewhere in the low 150's. Still, I do stir the mash for a good minute or two, to try to disperse.

But it's true that I'm not exactly trusting my dial or my digital 6" probe these days. So,
I am going to pick up a long-probe candy thermometer from BedBathBeerandBeyond for this next batch. It'll reach through most of the grain bed, so hopefully that will give me a more accurate reading.

This attenuation thing has GOT to be an issue with the mash though, right? Somehow, some way, it's GOT to be...

Do you have a dip tube to get the 1.5 gal below the FB? If not, that's a big problem. You're leaving fermentables behind and probably having to over sparge to compensate.

Gremlyn1 said:

Do you have a dip tube to get the 1.5 gal below the FB? If not, that's a big problem. You're leaving fermentables behind and probably having to over sparge to compensate.

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No, I don't have a dip tube. But my drain IS below the false bottom still, so I am getting some of that. I figured it out once, and I think it's actually 0.8 gallons which actually rests below the drain. So that's what I'm losing, I believe, as far as yummy fermentables goes.

But as a matter of fact, I already think I have to over-sparge some on smaller beers because my boil kettle is so wide (again, from MoreBeer), by boil off rate is ~25%. If I want a good, 60-min rolling boil, I've got to collect 7 gallons to end up @ 5.25. If I'm only mashing 7-8 lbs of grain, I've got to pump quite a bit of sparge water through to get my 7 gallons.

But hitting OG has never been my problem, and I haven't noticed any astringent flavors in my beers, so I don't think I've been sparging to a point where's it's negatively affected my beer. Then again, maybe my sucky-attenuated, thick-bodied brews are masking the tannins I have been collecting all along.

Am I in need of a better mash tun/narrower brew kettle?

I've just about given up on lower temp fermentation for ales and stay above 65F all the time now - because of the attenuation problem. It also takes longer for the conditioning with the lower attenuation. You might see if you can borrow a max/min temp monitor to make sure you aren't dropping below 63. I moved the temps to the 67-69 range and the attenuation problem went away. What is Wyeast's recommended ferm temp?

Obelisk said:

I've just about given up on lower temp fermentation for ales and stay above 65F all the time now - because of the attenuation problem. It also takes longer for the conditioning with the lower attenuation. You might see if you can borrow a max/min temp monitor to make sure you aren't dropping below 63. I moved the temps to the 67-69 range and the attenuation problem went away. What is Wyeast's recommended ferm temp?

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60-72 degrees for the pacman. (The tape on the carboy read 62-63, so you have to figure it's actually somewhere above that inside there with all that activity). But honestly, this is the coldest fermentation I've done. I'm usually brewing in the summer where I struggle to keep it below 72 degrees. My fermentations finish lickidy-split, but still finish too high. It ain't yeast count, because I've dumped batches directly onto a previous yeast cake, watched fermentation explode, and still stop short of the mark.

Only thing I can figure is that it's in the grain bed, either during the mash, or something during mash-out/sparging. Either that or I'm cursed.

try a 90 minute sacc rest. you should see your attentuation improve by a few points.

you might be getting all your starch converted but still have long chain sugars that can be broken down just by letting everything sit a bit longer.

rurounikitsune said:

try a 90 minute sacc rest. you should see your attentuation improve by a few points.

you might be getting all your starch converted but still have long chain sugars that can be broken down just by letting everything sit a bit longer.

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You know... I'll hit myself over the head with Das Boot if that's the answer. I never thought to go longer - always assumed that the 60-minute rule-of-thumb ought to apply to me as much as the next guy. But maybe not.

Thanks. I'll give that a go next time.

I now use an oxygen tank to aerate my wort which works wonderfully... However when I used to just shake it up... I would swirl the hell out of it for about 10-15 minutes... Attenuation is all about making your yeast happy in every way possible. Make sure you are pitching the proper amount and if you are using pacman yeast or a cal ale you should be fine raising that temp to the higher end of the spectrum. Also, for higher gravity ales, don't be afraid to give it some more aeration early in the fermentation. This is how I just got an imperial IPA from 1076 OG to 1010... and its clean.

yeqmaster said:

don't be afraid to give it some more aeration early in the fermentation. This is how I just got an imperial IPA from 1076 OG to 1010... and its clean.

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Really? I've heard that's a no-no.

How exactly do you do this? Are you talking about gentle swirls to agitate the yeast, or do you actually shake it? I presume you'd replace the airlock with a rubber stopper or something before doing that.

Or are you using the O2 stone for that?

I gotta get me one of those and right quick.

Maybe I'll try repitching some yeasties into my 1.016 FG Dry Stout and get it upstairs where I'm closer to 70?

I would recheck the calibration of you thermometer and hydrometer.Having experienced thermometer problems ... They can really mess you up if their off... Sometimes they can be off by a lot.This would explain an attenuation problem if your mash temp is off... Or your strike water for that matter.

I'll second thermo problems as a possibility. After buying a Thermapen I found my other thermometers (analog, digital, dial, alcohol etc.) were anywhere from 5 to 10 degrees off.

What are you using for grain? Is all of your base gtrain from the same batch by any chance? I had (have, actually) a bag of Golden Promise that no matter what I do with it I cannot get a beer to attenuate beyond 50%. If I use plain old 2-row or my Maris Otter everything works exactly as expected. Just a thought.