Always a super low FG... wha?

[luckybeagle]

I've brewed a few dozen AG batches and, no matter what I mash at or what yeast I use, I always seem to get very high attenuation. I don't think much of it when brewing Belgians due to adjunct sugars and naturally high attenuating yeast strains/the desire for a very dry beer, but I also seem to get it with other non Belgian strains:

WY1388: 94% average - Belgian Golden Strong, Blonde, Dubbel, Trappist Single (average mash temp: 149F for 60min. All finished around 1.005-1.008
Wy1214: 90% average - Tripel, BDS (149 mash). Finished below 1.010 IIRC)
WY1007: 88% average - Kolsch, Porter, "Irish" Dry Stout (151F mash on each). Finished 1.004-1.008

The list goes on. I don't think I've come close to 70-75% advertised by some of Wyeast's strains, which I know is typical--but my numbers just seem higher than coincidence.

• All fermentations are temperature controlled via Inkbird probe and chest freezer.
• All yeast pitches involve a starter or properly calculated slurry volumes (no direct cake pitches)
• I brew 3 to 5 batches on one yeast culture before "retiring" it down the drain.
• FG is reached in most cases within 4 to 7 days (no extended primary, have only secondaried once in my life)
• I batch sparge at 1.25 ratio and get 72 - 75% efficiency, depending on grain bill weight

What is the great mystery for such low FG's? Or are my numbers actually typical?

 

[grampamark]

Are you bragging or complaining?

 

[luckybeagle]

Are you bragging or complaining?

Complaining more than anything, and trying to figure out what in my process is causing this. My setup is simple and cheap. I give my carboys a good shake before pitching but no O2 aeration. My beers turn out with almost no residual sweetness, higher in alcohol than I'm targeting, which pushes some of my beers outside of style guidelines (such as an 8.8% ABV dubbel) and thinner in texture. The dryness and lack of sweetness is fine in Belgians, but overly dry in styles that call for more mouthfeel is a drag. My porter had none of that signature dessert porter body or sweetness. My current Dry Irish Stout is looking to finish at 1.005, which is making it come across as a little harsh for even an intentionally dry beer, and despite going easy on the roasted malts. I usually don't mash higher than 152F but I can't imagine I'd gain several points by raising it a few degrees?

 

[day_trippr]

I wouldn't be bragging but I'd definitely be wondering how three different strains that typically clock in at ~75% apparent attenuation have gone so far beyond. Even if the cold side gear is contaminated with wy1388 (diastaticus positive) I just don't see those numbers happening - and I don't see them resulting from even a prolonged low temperature mash.

It's a mystery...

Cheers!

 

[SEndorf]

This situation doesn't add up, so look to the simple first.
Calibrate your hydrometer, and ideally, get a three set that includes 0.98 - 1.03

 

[grampamark]

I was joking, of course, with my previous comment.

Your problem could be contamination, or it could be as simple as a measuring error due to an improperly calibrated hydrometer. The power of suggestion is strong. Seeing low numbers might make you think your beer is drier than it is.

Try some different yeasts. See if your hydrometer reads “1.000” in distilled water. Try mashing a little higher. Try a new, uncontaminated fermenter. Make one change at a time so you can keep track of what worked and what didn’t. And, good luck.

 

[Vale71]

WY1388: 94% average - Belgian Golden Strong, Blonde, Dubbel, Trappist Single (average mash temp: 149F for 60min. All finished around 1.005-1.008

WY1388 has been genetically classified as a var. diastaticus. If you're carrying it over as a contaminant in all subsequent fermentations than that could be responsible for all your beers been overly attenuated. I woudl suggest reviewing your sanitation practices to prevent any cross-contamination between batches.

 

[Gulo_gulo]

I usually don't mash higher than 152F but I can't imagine I'd gain several points by raising it a few degrees?

Only one way to know for sure, but 152F isn't exactly on the highest end. And I haven't noticed if anyone mentioned that your thermometer could be messed up, so what you think is 152F could be lower.

 

[Vale71]

Only one way to know for sure, but 152F isn't exactly on the highest end. And I haven't noticed if anyone mentioned that your thermometer could be messed up, so what you think is 152F could be lower.

You can't get 90% attenuation without sugar adjuncts by just mashing at the low end of mash temperature.

 

[Gulo_gulo]

This is a good read: https://www.homebrewersassociation.org/forum/index.php?topic=5384.0

At least check out the responses around #8 through #11... And #29... Or read the whole thing... attenuation percentage is not absolute.

 

[Vale71]

I don't know what you mean by "absolute" but there are limits on how fermentable an all-malt wort can be without the use of synthetic enzymes (limit dextrinase). This is due to how malt enzymes work and the structure of starch. At 90% you've already passed those limits no matter how low you mashed.

 

[luckybeagle]

WY1388 has been genetically classified as a var. diastaticus. If you're carrying it over as a contaminant in all subsequent fermentations than that could be responsible for all your beers been overly attenuated. I woudl suggest reviewing your sanitation practices to prevent any cross-contamination between batches.

I think this, along with user error/bad equipment explains it.

I went back with my refractometer and checked my stout last night. On Wednesday I was showing ~5.5 brix (OG was 11.3 brix, or 1.045--88% attenuation at FG 1.005), but last night it read 6.0 brix (1.010), which is obviously impossible. I brought out my trusty hydrometer and confirmed 1.010 (77.7% attenuation). This seems much more likely given the typical attenuation percentage of WY1007.

Even though the refractometer reads 0.0 brix with distilled water, I think I will rely on my hydrometer from here on out. Maybe it's a little more idiot proof. Maybe I put too much faith in the refractometer and really haven't been getting as high of attenuation as I thought.

I only used my hydrometer with the 1388 batches, so I can confirm those high attenuation numbers--but it'd make sense that there was some diastatic action going on--or that the 15% sugar adjuncts made that possible (or both).

Thanks everyone -- I knew it didn't add up but couldn't really figure out what was going on. I'll chalk it up to equipment error/user misunderstanding.

 

[Gulo_gulo]

My understanding is that refractometers aren't accurate when there is alcohol.

 

[Gulo_gulo]

I don't know what you mean by "absolute"

I meant the attenuation percentage range stated for a yeast by the manufacturer is not definitive; there are other factors. Another that was interesting to me that is discussed in the thread I linked to before is how flocculation can affect attenuation. Besides other factors like mash temp .

 

[luckybeagle]

My understanding is that refractometers aren't accurate when there is alcohol.

They can be adjusted for if you know the OG:

• If OG is 10 brix (1.040, before alcohol), and if FG reads 5.5 brix, FG is 1.010
• If OG is 12 brix (1.048, befofre alcohol) and if FG reads 5.5 brix, FG is 1.005

I don't know the raw calculation or the exact science behind it, though. I'm also a little skeptical/curious/not knowledgable beyond this. At what point does the presence of alcohol affect the reading? For example, if a hydrometer reads 1.045 before pitching, and I take a gravity reading 12 hours later and show 1.040 (indicating just 0.65% ABV), will the refractometer need to be "adjusted" for the presence of alcohol? Or does it take more than just a tiny amount of alcohol to skew the reading?

I really like how little liquid it takes to get a reading--much better than dipping my wine thief in three times to collect enough volume, but a hydrometer is about as straightforward as it gets. Maybe I'll go back to the old school method for a little while.

This is the calc I've been using: https://brucrafter.com/convert-brix-to-sg/

 

[SEndorf]

I find this one from MoreBeer easier to use, and I can track with it.
In the small type under "Refractometer" there is a link to the spreadsheet

https://www.morebeer.com/category/refractometers.html

 

[jrgtr42]

My understanding is that refractometers aren't accurate when there is alcohol.

There's an adjustment / calculation for that. I use Brewer's Friend one.
https://www.brewersfriend.com/refractometer-calculator/
I've had a refractometer for a while, and for the first several batches, I'd back up my readings -
check with refract and then check with the hydrometer.
The one time I had a drastically different result I went back and checked - yep, an ID-10-T error (user boo-boo)
Once corrected, it came out exactly the same. I generally don't use the hydrometer anymore.

As far as the OP goes, that FG isn't far off for the single, and depending on brewer, the triple.
But 149 is a pretty low mash temp - you'd be amazed what a few degrees difference makes.
For instance, I have a stout that I've brewed a bunch of times. Once I got low on my mash temp, at 152, and it came out really thin tasting - I called it a porter and went with it.
155 it comes out much thicker feeling, with enough sweetness to counter the roast.
For the OPs dubbel and Quad, I'd recommend upping the mash to around 153 or so - that will make a big difference.