3rd beer stuck at 1.020

a little background - the first was a nice ipa that started out at 1.065 and finished stuck at 1.020 (tastes good). Was a little too excited and brewed another before that one finished and it started at 1.055 and finished at 1.020 (a little sweet). I've been all over the boards and various sites and realized I underpitched my yeast significantly in the first two batches (i never made a starter).

So for my third beer I wasn't going to make that same mistake, but guess what, I'm stuck again. Here are the specifics:

WLP001 - made a liter starter according to beersmith instructions to get the proper amount of yeast.

Pitched the starter yeast at 70 degrees after aerating the crap out of by shaking the 6.5 gal carboy like madman for a couple minutes.

Fermented in a room that stays 63-69 degrees. On average its more around 67. First 4 days of fermentation it sounded like a machine gun the amount of bubbles blowing through the blow off tube. day 5 it stopped. Checked the gravity on day 7 and 8 both at 1.020. Day 8 i swirled and pitched a half starter I had in the fridge (same wlp001) and am raising the temp in the room to around 72. yes, i've read not to repitch, but I've got to do something. Twittling my thumbs hasn't worked

Like any new brewer I'm freaking out... again.

Thank you in advance, you guys have been a major help in learning how to brew. I appreciate it.

Explain your gravity measurement process.

Lesson 1: Don't use BeerSmith for calculating starters. It's a great program for most things, but making starters it is not good at.

You didn't tell us the OG or volume of the third beer.

hydrometer in glass flask. After my first I checked the calibration and it all checks out.

First measurements were before yeast pitching and aeration around 75 degrees. Now it's at 68, the current temp of the beer fermenting.

Third beer OG was 1.070 with 5 gallons. Made a starter that should have increased the cells to 250bill

Are these extract batches? It's a fairly common problem to have a highish FG with extract since you don't have the control over the fermentability of the wort like you do in an all-grain brew. Search around for the "curse of 1.020" and you'll see it's pretty common with extract beers.

Mrmalty.com is saying for a 1.070 beer at 5 gallons with supremely fresh yeast you'd be looking at a 3 liter starter to get the yeast count up to 241 billion.

Now if you used a stir plate with your starter, then you'd only need 1.14 liters.

bdh said:

Are these extract batches? It's a fairly common problem to have a highish FG with extract since you don't have the control over the fermentability of the wort like you do in an all-grain brew. Search around for the "curse of 1.020" and you'll see it's pretty common with extract beers.

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This is not something I have ever experienced when making extract kits. If fresh ingredients are used, along with proper yeast amounts and sufficient fermentation control, I see no reason for fermentation to suddenly stop.

DenverUSMC said:

This is not something I have ever experienced when making extract kits. If fresh ingredients are used, along with proper yeast amounts and sufficient fermentation control, I see no reason for fermentation to suddenly stop.

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It's not that fermentation stops prematurely, just that extract can contain a fair amount of unfermentable sugars - leaving you with a fairly high FG. For beers that have OG's in the 1.065-1.070 range like the OP mentions having a FG of 1.020 is about what I'd expect.

THis batch was all grain. my previous 2 were partial. now, I will say towards the end of the all grain brew I was getting a little toasty, but the main work was done. That's a long time to sit around drinking beer.

Don't ask about the grain bill - i started with a list with conversions written one way, but my beer supply place had them another. Poor conversions in the head, ending up with a lb extra after winging it could be another reason.

my mistake I checked my notes and I did use a 48 ounce starter. Started it two days ahead in a old sanitized milk jug. It was frothing up good.

Again, I appreciate all the help. Is there anything I can do now to get this thing going again? or is this my beer and I'd better like it. Scared to brew another.

Iamslow said:

THis batch was all grain. my previous 2 were partial. now, I will say towards the end of the all grain brew I was getting a little toasty, but the main work was done. That's a long time to sit around drinking beer.

Don't ask about the grain bill - i started with a list with conversions written one way, but my beer supply place had them another. Poor conversions in the head, ending up with a lb extra after winging it could be another reason.

my mistake I checked my notes and I did use a 48 ounce starter. Started it two days ahead in a old sanitized milk jug. It was frothing up good.

Again, I appreciate all the help. Is there anything I can do now to get this thing going again? or is this my beer and I'd better like it. Scared to brew another.

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How long has it been sitting at 1.020? You could try raising the fermentation temperature a little bit and swirling the carboy/bucket to see if you can get anything else to ferment out, but a FG of 1.020 doesn't mean the fermentation is necessarily stalled.

What was your mash temp? You said it got a bit hot towards the end, so if you had a warm mash a 1.020 FG from a 1.070 OG wort might just mean it's done fermenting.

LandoLincoln said:

Mrmalty.com is saying for a 1.070 beer at 5 gallons with supremely fresh yeast you'd be looking at a 3 liter starter to get the yeast count up to 241 billion.

Now if you used a stir plate with your starter, then you'd only need 1.14 liters.

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looks like i underpitched again. Dang the yeast!

You may have under pitched a little, but with your SG of 1.070 and the fact that WLP001 attenuates 73-80% per White Labs, your very close. With those figures should finish roughly at 1.014-1.019

stvo said:

You may have under pitched a little, but with your SG of 1.070 and the fact that WLP001 attenuates 73-80% per White Labs, your very close. With those figures should finish roughly at 1.014-1.019

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Is there a good thread for dummies that explains this math somewhere? I don't even know how to search for it but, I'd love to actually know that what I'm pitching is going to be adequate rather than just trusting the package.

And, back on topic....
I had a brew get stuck at around 1.020 too. It was an extract brew. I moved it to secondary and (out of newbie panic) pitched some champagne yeast. As I understand it, champagne yeast shouldn't have an impact on the final flavor of your beer.

In my case the yeast didn't really do a whole lot. I dropped, maybe another couple points.

Don't blame the yeast, they can only work with what they are given. You may not have had the perfect pitch of yeast, it still is close enough to ferment properly. I think its a wort issue and not a yeast issue.

What FG are you expecting? Do you know what the extract you used is supposed to ferment down to? What did temp did you mash at?

And do tell about mashing temps....

Shred said:

Is there a good thread for dummies that explains this math somewhere? I don't even know how to search for it but, I'd love to actually know that what I'm pitching is going to be adequate rather than just trusting the package.

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Well, let's see...

The yeast in question has an attenuation rate of 73-80%.

The OG was 1.070. The FG was 1.020.

70 * .73 = 51.1
70 * .80 = 56

So you'd expect to drop between 51.1 and 56 points from the OG of 1.070, giving you an expected FG of between 1.019 and 1.014. The actual FG was 1.020, so it was a point lower than the low end of the expected attenuation.

Now, to figure out your estimated ABV, you'd take the OG minus the FG and then multiply that number by 131.25.

(1.070 - 1.020) * 131.25 = 6.56% ABV (estimated)

It's day 10 and measured again after raising the temps and swirls it still sits at 1.020. I'm calling this one a learning experience. I will be transferring this into the secondary and dry hopping tonight.

for another that asked: mash temps were 5 gallons at 148F when mixed in a 10 gallon round tun for an hour, then two batch sparges with 2.5 gallons with the first around 158 and second around 168. Sat for 10 min each. Boiled down approx 7.5 gallons to get to 5.

Cooled it with a wort chiller and a big milk jug full of ice. Yes, that is where I got toasted (drunk) and threw in the big ice jug unsanitized. Yes, I know I understand the risks of contamination, and I learned a valuable lesson. Don't break into scotch and cigars when brewing. It did drop in temperature pretty fast though.

Last question and most important, how can I make sure I do not underpitch again. What is the best way to find out how much yeast is needed. That's seems to be my main issue.

I appreciate all the help and advice. Thanks again

Another thought. What temperature did you have when you read your gravity samples. Most hydrometers are calibrated for 60 degrees. If your sample is not there you have to calculate for the difference. That may make a couple of points difference.

For yeast pitching rates see mrmalty.com and yeastcalc.com. There is a lot of reference there.

Iamslow said:

Last question and most important, how can I make sure I do not underpitch again. What is the best way to find out how much yeast is needed. That's seems to be my main issue.

I appreciate all the help and advice. Thanks again

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Well, if you really want to understand how to come up with the yeast pitching rate by yourself, then I'd recommend reading this book. Great book with more information about yeast that you ever could imagine.

But if you just want the answer to the question of, "so how many packages of yeast / liters of starter do I need to pitch?" then just go to a yeast calculator site like mrmalty.com or Brewer's Friend.