Why Is My Final Gravity So High?

So I'm currently making a chocolate milk stout. Something pretty close to this. Only real difference is that I I added a half a pound of oats and cut a bit of the roasted barley and dropped the lactose by 25%. I was also a but lazy in my conversions to KG and added a tad more grain (just a tad) of each type.

I did an all grain BIAB and my efficiency was much better than expected and the OG was 1.077 after lactose (1.068 before). I mashed at 155.

I started off with Windsor yeast by either under pitched or let things get too cold (they dropped to about 65 degrees) and while the ferment went nuts for the first 24 hours and dropped way down to 1.048, it seemed to get stuck and activity just about ceased.

Concerned, I added some US-05, gave it a gentle stir, and put a heater near it to bring it back up to about 70 degrees. The activity picked up again things hummed along for another week. I noticed activity was slowing down again so I checked the gravity and it's down to 1.038, which is better, but that's still 1.03 after accounting for the lactose which seems way too high.

Am I wrong in expecting a lower FG? I've never had a final gravity over 1.017 but this is also the darkest beer I've ever made. I'm going for chewy and sweet, just not quite as chewy and sweet as I've got.

So my questions...

1. Is a gravity of 1.3 for a beer like this more common than I think?

2. What causes such a high final gravity? I assume starches that didn't convert, but I'm not clear where I went wrong exactly. I know the mash temp was high, but I didn't think it would cause this.

3. Is there anything else I can do without adding an enzyme that will convert everything, leaving me with a much dryer beer than I was going for?

Really I'm just curious to get some feedback so I can continue to learn and get a better sense for this whole process. The beer really does taste good. But if I could bring that gravity down to 1.02 (after lactose) I think it would be amazing.

Thanks in advance for any ideas/suggestions.

1. No

2. The problem wasn't conversion, your efficiency was good, so the starches we re converted. Your nah mash temp wasn't that high unless your thermometer is off. Are you using a refractometer?

Thanks for the reply.

I'm not totally clear on what is fermentable and what is not in the darker malts such as crystal, chocolate, roasted barley, oats, flaked barley etc, but my understanding was that they would add some unfermentable sugars to the mix. Am I misunderstanding that or would that in no way account for a final gravity in the high 2s?

Is the kind of thing where if my hydrometer is registering then the starches have been converted, or would the gravity still be high even if I hadn't converted the starches?

As for the other question, no, I'm not using a refractomerter. Just a run of the mill hydrometer. Same with the thermometer. It's a pretty standard metal thermometer from a home brew shop. I do my best to stir up the mash and mix it around a good deal, as well as take the temp in multiple areas. Still, there is always room for error. Especially with a deep pot like that. Even with the stir, it could be hotter near the bottom.

I've only done one other brew with this set up and it was a pale ale. The final gravity was a tad higher than the recipe suggested. It was supposed to be 1.01. I got 1.07. I didn't figure that was anything significant. Certainly not compared to what I have this time around. But on that brew I mashed at 152 and it dipped a bit more than this brew did. So I suppose I could be mashing hotter than I think I am.

If that is the case nad there are unconverted starches in there, do they make it taste sweet, or just add body? Because of the lactose I have in tehre it's really hard for me to know the source of the sweetness I taste.

If anyone else has any insight I'd love to hear it. The exact recipe I used was as follows (I did the measurements in KGs, but have converted it to lbs below (hence the awkward totals):

----

8.81 lb - Maris Otter
.66 lb Flaked Barley
.66 lb rolled oats
.66 lb UK - Chocolate
.66 lb Roasted Barley
.66 lb UK - Brown
.66 lb Dark Crystal 120L
12 oz Milk Sugar

Mashed at 155 for an hour, boiled for 70.

Hops:
1.5 OZ Fuggles (60 Minute)

Additions:
.3 OZ Cacao Nibs soaked in vodka for two weeks, added after noticable fermentation stopped.
1 1/4 tsp Irish Moss added for last 15 minutes of boil.
wine yeast nutrient

Windsor yeast and US-05 yeast (added the latter after things seemed to be stuck.

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is this high FG at 2 weeks, 3weeks, a month?
whats the current time frame on this?

A 50% specialty malt grain bill with 3/4lb lactose isn't good for a low FG

Sorry about that. I started fermenting 18 days ago. The recipe I was more or less copying (with a few small changes) was this one. But I hear you on the specialty grain ratio. I'm not totally clear on how fermentable specialty grains are. I have read they are mostly not fermentable, but then I see recipe containing a lot of them that have pretty low gravities. Does a high 2 gravity seem like it could be normal for a recipe like that? Per the original post, I am accounting for the lactose. The gravity with the lactose is actually 1.038.

It might just stay that high.
give it another week and if its still high, you could add some simple sugar to thin it out. there is enough other stuff in there that it wont hurt it.

Thanks, what do you mean exactly? How would adding sugar thin it out? Dp you mean a water and sugar mixture to keep the alcohol up, while lowering the sweetness? And by simple, do you mean just plain old cane sugar?

What strike temp did you hit before adding your grains? I find that a lot of software overestimates the temp loss on BIAB. With such a high volume of water, I find the temp loss after adding grains on my system is usually only a degree to maybe a degree and a half. Beersmith tells me to heat water to about 5 degrees hitter than my mash temp even after telling it not to account for equipment, which otherwise drives the calculated temp needed even higher.

It's possibly if your new to BIAB and using software that you are mashing higher than you think. The probe on those standard thermometers isn't that long so you're mostly getting surface readings and the bottom can be much hotter. I added a weldless thermometer to my kettle for this reason. This is a long way of saying you may be mashing higher than you think which is why your pale ale also finished high. I had this exact issue with my system initially and all my beers were finishing high until I figured out to undershoot the beersmith target strike temp by a few degrees.

Here are the potential problems that I can see, just speaking from my own experience:

1) Thermometer not calibrated, so sugars didn't convert properly. Double check your thermometer both at freezing and at boiling. It's also better to invest in a decent digital thermometer.
2) Temperature fluctuations caused the yeast to become stressed and go dormant. Bringing the temp back up could arouse them, but you might need to repitch.
3) Not enough aeration before pitching the yeast. This is where I had the most trouble when I got started. Most of my beers were under attenuated. Once I got an oxygen stone and a tank, my beers became more consistent. Many people have success with air pumps, paint mixers, and the 'shake-and-pray' method, as well. For an OG of 1.077, though, you're better off with pure O2.

Your grain bill is fine. You only have 25% specialty grains, and at that mash temp, I'd expect you to end up in the low twenties.

Don't add sugar. That's hit and miss. It could arouse the yeast, but then they might only consume the sugar you added, not the more complex sugars that are already in there.

If it were me, I would wait one more week, and check again. If it's not down below 1.025, I would make a starter with a highly attenuative liquid yeast and repitch. I know this yeast doesn't fit the style and can throw some different flavors in there, but one I like to use when my darker beers don't attenuate is Wyeast 3711. It's a saison yeast, but at lower temperatures, the flavors it gives off will be less pronounced. I also like the complexity it adds to stouts. That's totally up to you though, you might want to consider WLP099 Super High Gravity Yeast. That one is more neutral.

Windsor yeast is very low attenuating. I used it twice and gave up on it.

Thanks everyone for the advice. It's all very helpful. A few different responses...

BPal75 said:

What strike temp did you hit before adding your grains? I find that a lot of software overestimates the temp loss on BIAB. With such a high volume of water, I find the temp loss after adding grains on my system is usually only a degree to maybe a degree and a half. Beersmith tells me to heat water to about 5 degrees hitter than my mash temp even after telling it not to account for equipment, which otherwise drives the calculated temp needed even higher.

Click to expand...

I've thought a lot about this and I think you could be right. The advice I got was to get my strike temp 10 degrees above where I wanted it so I started at 165 and I do remember asking myself "If my thermometer is off and it is over 170 down at the bottom will I be killing the enzyme's potential here?" I'm not clear how that works. Nonetheless, I stirred the grains while holding the thermometer in the pot until I got to 155 and then put the lid on. I had to goose the temp a few times to get it back up during the mash. But I was concerned about the possibility that the temp was a lot hotter down at the bottom. Though stirring things up didn't really indicate that it was.

TheZymurgist said:

Here are the potential problems that I can see, just speaking from my own experience:

1) Thermometer not calibrated, so sugars didn't convert properly. Double check your thermometer both at freezing and at boiling. It's also better to invest in a decent digital thermometer.
2) Temperature fluctuations caused the yeast to become stressed and go dormant. Bringing the temp back up could arouse them, but you might need to repitch.
3) Not enough aeration before pitching the yeast. This is where I had the most trouble when I got started. Most of my beers were under attenuated. Once I got an oxygen stone and a tank, my beers became more consistent. Many people have success with air pumps, paint mixers, and the 'shake-and-pray' method, as well. For an OG of 1.077, though, you're better off with pure O2.

Your grain bill is fine. You only have 25% specialty grains, and at that mash temp, I'd expect you to end up in the low twenties.

Don't add sugar. That's hit and miss. It could arouse the yeast, but then they might only consume the sugar you added, not the more complex sugars that are already in there.

If it were me, I would wait one more week, and check again. If it's not down below 1.025, I would make a starter with a highly attenuative liquid yeast and repitch. I know this yeast doesn't fit the style and can throw some different flavors in there, but one I like to use when my darker beers don't attenuate is Wyeast 3711. It's a saison yeast, but at lower temperatures, the flavors it gives off will be less pronounced. I also like the complexity it adds to stouts. That's totally up to you though, you might want to consider WLP099 Super High Gravity Yeast. That one is more neutral.

Click to expand...

Thanks, as mentioned above, I think you're right and I need to invest in a good digital thermometer. And knowing that with that grain bill my target FG should be in the mid 2s is really helpful. I have no idea how to calculate that. There is still some very minor activity in the carboy so I'm hoping that another week or two will bring it down. And just 5 points doesn't seem impossible at all. I am assuming you meant 1.025 without accounting for the lactose? I took readings before and after adding the lactose so I know it's adding .008 to the gravity. My gravity at last reading was 1.38 before accounting for lactose. 1.03 if I factor it in.

For aeration all I did was bung the carboy up and shake the crap out of it. But I did try re-pitching with US-05 when I got the impression that things were stuck. Unfortunately though I didn't have any malt or extract so I didn't do a starter.

My plan at this point is to give it a good long time in there (about 30 days) and then take a reading. If the gravity is still problematic then I was thinking I'd rack into a secondary and add a little dextrose (just to make sure the yeast produce enough C02 to keep things safe with what would be quite a bit of head space after pulling the beer off of 3 or 4 inches of sediment (I don't have a smaller carboy to go into). My thinking being that the aeration and the new sugar might kickstart things. My biggest reason for doing this is actually just to insure that I don't get bottle bombs. Does that seem like a sound idea?

Bobby_M said:

Windsor yeast is very low attenuating. I used it twice and gave up on it.

Click to expand...

Yeah, I knew that going in but didn't expect such a problem. But I did repitch with US-05. It helped a little, but not tremendously.

Thanks again for all the great advice.

Microphobik said:

My plan at this point is to give it a good long time in there (about 30 days) and then take a reading. If the gravity is still problematic then I was thinking I'd rack into a secondary and add a little dextrose (just to make sure the yeast produce enough C02 to keep things safe with what would be quite a bit of head space after pulling the beer off of 3 or 4 inches of sediment (I don't have a smaller carboy to go into). My thinking being that the aeration and the new sugar might kickstart things. My biggest reason for doing this is actually just to insure that I don't get bottle bombs. Does that seem like a sound idea?

Click to expand...

I think that sounds pretty good. Even with the Lactose, though, I'd still hope for you to come in below 1.025. I have a stout recipe that has an OG of 1.075 with a pound of Lactose, and I can usually get it down to 1.018. Part of that is mashing at 150, part is fermentation temp control, and part is using O2. Before the ferm temp control and O2, I would have been lucky for it to finish.

Gotchya, okay. Good to know. I'm not as close as I thought then... Doh! I think a major factor here is temp control on every front. My thermometer is probably not quick and accurate enough and the termometer on my carboy is just one of those stick on ones and I suspect it's off. I am in New Zealand and it's winter here and we live in a fire place heated home, so it can get quite cold at night. I have a heater near the beer to keep it consistent, but I didn't start using it until the ferment got stuck. And even with it, I have a feeling that the thermometer is reflecting the temp outside of the carboy, more than what is going on inside of it.

Could be oxygen but both batches I have done with this set up exploded with fermentation initially. This stout blew the airlock off within 3 hours of pitching, it was crazy. So my assumption was that the oxygen was good enough and that the temp just got too cold and things went dormant too fast and since then it's been a struggle to wake things back up significantly. But who knows.

Oh well, I'll get there one way or the other. Thanks again.

Just had my first bottle from the batch. Not bad. Probably not the best I'll ever make, but not one I would be disappointed with if I had bought it at a pub either.

Never got the gravity below 1.036 (1.027 after accounting for the lactose). But very surprisingly it really isn't sweet at all. Just a tiny hint. Enough that people notice the sweet factor if you tell them it's sweet first, but they don't if you don't mention it. Very surprised with such a high FG. No carbonation issues either. came out perfect.

I'm convinced I was just mashing much higher than I thought and that the top of the mash was just much cooler than the bottom. I now subtract a couple degrees on my target mash temps to adjust.