Low attenuation problems

[Torchiest]

I've been having a problem getting my bigger beers to hit their target gravities. I've been missing by anywhere from 5 to 10 points. It's kinda come to a head at this point, because I've got my biggest beer ever (OG 1.090) that's been sitting in primary for 17 days now. The SG is currently 1.031. That's only 65.6% attenuation. The predicted FG is 1.020, according to BeerSmith.

I'm using White Labs WLP530 Belgian Abbey Yeast, which I specifically picked because of its high alcohol tolerance, up to 15%, and its high attenuation, 75-80%. I guess I'm just bothered because it seems like it should be ready for secondary by now. Maybe I'm being impatient with this massive beer. Can I safely give it another week or two in primary? It still seems to be bubbling a few times per minute.

The annoyance stems from the fact that most of my beers seem to have low attenuation. I just figured my average, and for the first fourteen batches I've done, it's 71.6%. Is that low? What kind of attenuation does everyone usually get?

 

[clayof2day]

What's your pitch rate (1 vial? starter? 2 vials?) How do you aerate? What was your mash temps (if you're mashing)? What was your grain bill like? These are all factors that are going to affect your FG. Usually low attenuation can be attributed to insufficiently healthy yeast pitched, or insufficient aeration.

 

[Torchiest]

I normally pitch a one quart starter made from a single vial of white labs. My aeration "method" is that I brew at work, carry the carboy shakily to my truck, drive it home with nice abrupt stops and starts shaking it up all the way, then shakily carry it up two flights of stairs to my apartment, and then shake it around for a few more minutes for good measure. I've only done one partial mash so far.

 

[EALynx]

Torchiest, Are you able to maintain a constant temp when you are fermenting? Sometimes the yeast will slow down or even shut down when they experience vast changes in temp. If this isnt your problem, then I would look into larger starters or even your grain bill and your mash temps. Other than that, Someone else will have to help you.

Cheers,

ealynx

 

[david_42]

Bigger beers can be a real pain to finish. You should probably get some kind of aeration system, as shaking will only put 6-8 ppm O2 into the wort. An aquarium pump and stone will double that, O2 injection quadruple. Strong yeast growth as it adapts to the wort is critical for big ales.

I'll put my pump on a timer, so it runs for 15 monutes every two hours for the first 8 hours. One pro I know actually injects more O2 at 14 hours for his biggest ales.

 

[Torchiest]

Thanks for the suggestions. I've been thinking I'll need to get some sort of aeration system for my bigger beers, as they tend to be the ones that struggle to finish out. Anything I've done that started below 1.060 has come out pretty well; it's the big ones that only hit 65% attenuation or so. Still, this mega beer is still popping out bubbles slowly, so I'll check it again in a few days and see if it's still dropping grav points.

 

[Torchiest]

I've got my biggest beer ever (OG 1.090) that's been sitting in primary for 17 days now. The SG is currently 1.031. That's only 65.6% attenuation. The predicted FG is 1.020, according to BeerSmith.

I checked this afternoon, and it's down to 1.029 after six more days. It's been 23 days in primary. Any advice on keeping it in primary longer, or just going to secondary? I'm becoming mildly concerned about the trub.

 

[BierMuncher]

I'm not suggesting a belgian yeast connection, but here is a discussion about high krausening yeast that actually gets beached on the carboy walls and effective reduces the yeast available to do their job.

Take a look

 

[Torchiest]

I'm not suggesting a belgian yeast connection, but here is a discussion about high krausening yeast that actually gets beached on the carboy walls and effective reduces the yeast available to do their job.

Take a look

That's really interesting, because this batch did have a massive start and multiple blow offs early on. It does have a major crusty coating in the top part of the carboy, much like your image in the other thread. Should I give it a swirl or let it be for another week or so? I got two points in the last six days.

 

[Evan!]

Give it a swirl and see what happens. Can't hurt. Just don't splash.

And I second the above suggestion: get yourself a mechanical aeration method. After I got my $30 aeration kit from AHS, my attenuation averages went up by 10% or so.

 

[Bobby_M]

I tend to harp on this subject often. The problem with the shaking method, especially in your case is that you only exposed the headspace in the carboy to the wort. This headspace is only 20% oxygen and even if you got it ALL absorbed (unlikely) it's a low amount of oxygen. I would think though that pitching a starter would tend to have enough yeast cells to get the job done if the starter was really well oxygenated.

I think what you observed, seeing a large blowoff right after pitching, was a moderate cell count going directly into anerobic mode (fermenting). If the O2 level in the wort was a little higher, you would have seen a slightly longer lag while cells continued to reproduce. In the end, attenuation would be slightly better because more cells would be ready to ferment.

 

[Torchiest]

Give it a swirl and see what happens. Can't hurt. Just don't splash.

And I second the above suggestion: get yourself a mechanical aeration method. After I got my $30 aeration kit from AHS, my attenuation averages went up by 10% or so.

Yeah, I really need to do that. 10% more would be nice, cuz like I said, I'm barely getting 70% most of the time.

I tend to harp on this subject often. The problem with the shaking method, especially in your case is that you only exposed the headspace in the carboy to the wort. This headspace is only 20% oxygen and even if you got it ALL absorbed (unlikely) it's a low amount of oxygen. I would think though that pitching a starter would tend to have enough yeast cells to get the job done if the starter was really well oxygenated.

I think what you observed, seeing a large blowoff right after pitching, was a moderate cell count going directly into anerobic mode (fermenting). If the O2 level in the wort was a little higher, you would have seen a slightly longer lag while cells continued to reproduce. In the end, attenuation would be slightly better because more cells would be ready to ferment.

I had about a fifteen hour lag, so it didn't exactly jump right out of the gate. I totally undestand your point though. Again, I think the big issue is that it was such a big beer to start. Now I'm considering throwing a packet of Nottingham in there to see if it can finish the job, maybe give me another ten points. It should have enough nutrients to get going okay, right? My understanding is you don't really need to aerate or make starters for dry yeast. Thoughts?

 

[Torchiest]

Bump. Would a package of Nottingham be pointless? Should I rack along to secondary at 1.029? Or even, heaven forbid, use some beano?

 

[BierMuncher]

Bump. Would a package of Nottingham be pointless? Should I rack along to secondary at 1.029? Or even, heaven forbid, use some beano?

Please don't use beano. (don't get me started)

Did you give it a swirl yet? Any results? If you saw a lot of white "cream" falling to the bottom, that would have been yeast and should have done it.

Otherwise, there's no harm in pitching the Nottingham. You'll just end up with a bigger yeast cake, assuming there are fermentables.


I'd say wake up the yeast (swirl) or pitch some yeast and leave in the primary through the weekend.

 

[joejoe1881]

I tend to harp on this subject often. The problem with the shaking method, especially in your case is that you only exposed the headspace in the carboy to the wort. This headspace is only 20% oxygen and even if you got it ALL absorbed (unlikely) it's a low amount of oxygen. I would think though that pitching a starter would tend to have enough yeast cells to get the job done if the starter was really well oxygenated.

I think what you observed, seeing a large blowoff right after pitching, was a moderate cell count going directly into anerobic mode (fermenting). If the O2 level in the wort was a little higher, you would have seen a slightly longer lag while cells continued to reproduce. In the end, attenuation would be slightly better because more cells would be ready to ferment.

The only 20% = 200,000ppm, compared to the 9-10ppm needed in the wort so there's plenty of oxygen in the headspace.

If you don't pitch enough yeast into a big beer it doesn't matter how much O2 you pump in. Yeast grow best in high oxygen, low sugar environments, 50mg/L and lower of glucose. A high gravity beer wort can have sugar levels as high as 250g/L. So when you pitch your yeast into your wort they'll lean toward anaerobic regardless of the amount of oxygen.

My advice would be get a stir plate and pitch more yeast. Shaking is more than enough for 5 gallons.

 

[Torchiest]

Please don't use beano. (don't get me started)

Did you give it a swirl yet? Any results? If you saw a lot of white "cream" falling to the bottom, that would have been yeast and should have done it.

Otherwise, there's no harm in pitching the Nottingham. You'll just end up with a bigger yeast cake, assuming there are fermentables.


I'd say wake up the yeast (swirl) or pitch some yeast and leave in the primary through the weekend.

I didn't swirl. I'm going to the LHBS Saturday morning to pick up a packet of dry. I'll swirl, pitch the yeast, and cross my fingers.

 

[Torchiest]

It's been about 24hrs and no activity after adding dry yeast. I'm going to rack it to secondary either today or tomorrow. It's been about four weeks in primary, and whether or not it's going to ferment any more, I think it needs to be moved off the trub.

 

[BierMuncher]

At 7.9%, I'd say you're ready. That's a bigger brew than I could handle.

 

[Torchiest]

Well, at 48 hours, I've got a massive 0.5mm krausen, and about two bubbles per minute.

I think I'll leave it until Thursday, my next night off, and rack it to secondary then. I'll predict 1.025 as my final final target. Let's see how close I get.

 

[Willsellout]

My last couple beers have not finished below 1.020 and it's bothering me. Of course they were a bit higher OG's 1.062 and 1.061 respectively. They finished at 1.025 and 1.021. I'm aerating with pure O2 and pitching a 1000 ml starter but I can't seem to get my beers to finish where they are supposed to. This has been the story since I began brewing..they all finished high for some reason. I haven't been able to pinpoint my problem yet. My Amber that is currently fermenting I think I am going to re-aerate and pitch some nottingham to try and get it to finish lower.


Dan

 

[Torchiest]

...My Amber that is currently fermenting I think I am going to re-aerate and pitch some nottingham to try and get it to finish lower.


Dan

Just a note, I don't think re-aerating is a good idea. I think that would give you the dread wet-cardboard flavor, perhaps. I didn't re-aerate mine, I just pitched more yeast. But, I could be wrong.

 

[Willsellout]

Yeah it's a little too late for me to aerate again..well I'll rack it to secondary and taste it again in a couple weeks. If it turns out how I think it will, it won't ever see a bottle.


Dan

 

[Torchiest]

At 7.9%, I'd say you're ready. That's a bigger brew than I could handle.

Well, checked it today, no real change, but I went ahead and racked it to secondary. At least there will be a bit more yeast come bottling time.