First BIAB - Very low OG

[StrangeHaze]

Just looking for opinions on what I did wrong and what I can learn for next time. I did my first BIAB (second brew period), found a recipe and used software to scale from 6gal to 3gal (fermenter volume). Software suggested I start with 5.8gal into the kettle which I thought was a bit much, but figured "hey, what do I know". From research I did, it seemed I just had too much water and had I boiled the water longer and gotten it down to what would be approximately 3gal into the fermenter, I would likely have had a better OG.

Still, anything else I could've done differently or anything pop out as wrong with the recipe? Or does it come down to the water volume.

Grain Bill
3.25lb Viking Malt Pale Ale2 Row
1lb Weyermann German Pilsner Malt
.5lb Viking Malt Caramel 30 (10L)

Measurements
Expected OG: 1.044
Actual OG: 1.024
Water into kettle: 5.8gal
Pre-boil: 5.5gal
Into fermenter: 4gal

General Steps
Mash @ 149 for 30 minutes
Boil for 90 minutes adding hops along the way

I would have kept boiling the water had I known I was so off with my OG, however I had to add hops and whirlpool at flameout, so I figured I'd let it cool in the hydrometer while I whirlpooled. Hopefully just boiling down to the 3gal it suggested would've taken care of it and my batch will still turn out, but again, just looking to learn if the opportunity arises.

 

[Carolina_Matt]

When I plug that recipe into Brewers Friend, I get 55% efficiency. The recipe seems to have assumed 75% efficiency.

Part of it might be the 30 minute mash, rather than 60 minute. But the most likely culprit is the crush/grind. Did you mill them yourself, or buy them already milled? I have my own mill (Cereal Killer) and I crush as finely as it goes.

 

[Immocles]

Correct water volume would have definitely gotten you closer to your target. You're a healthy gallon over your target. Other things to be aware of are grain crush, and hydrometer sample temperature. That threw me off for a few gravity points my first couple brews.

 

[McKnuckle]

Just piling on, but while there are many factors in achieving a target OG, your water volumes were far off. Stick with correcting that first, then see what remains to be improved.

For a desired 3 gallons into the fermenter, add back all of your presumed losses to get your starting volume:

Left in kettle, including hops absorption, one cup or 0.06 gallons
Evaporated over one hour, 0.5 gallons
Absorbed into grain, 0.09 gal/lb* @ 4.75 lbs = 0.43 gallons
*No squeeze, just a long drain til it drips

That's 0.99 gallons, which we'll round up to an even 1.

So you should have started with 4 gallons of water given the above assumptions. Do a water-only run to determine your estimated boil-off rate. Correct the other numbers to suit your process.

 

[moreb33rplz]

Poster above says that calculates out to 55% efficiency. FWIW, I BIAB on a stove and do 2.5-3 gallon batches, and I average about 60% efficiency over a dozen or so brews. I tried lots of things: super fine grain crush, squeezing the bag, mash temps, none of it really made a difference. I think for me a lot of it is the amount of wort/trub/hop material I leave in my kettle when I rack it out to a fermenter.

TL;DR - 55% efficiency for BIAB isn't unusual. Use more grain, boil with less water.

TL;DR 2 - what everyone else says, you have way more wort in your fermenter than calculated, so of course your OG will be lower.

 

[Bill Hopper]

I'm having similar issues as I am trying to convert 5 gal recipes (or 5 gal recipe kits) into 3 gallon batches. Not as extreme though. I'm expecting 1.044 and I'm getting 1.040. In the first batch I added some light DME to get the gravity up while I was boiling off. I'm not sure that was the right thing as it seemed to introduce some flavors I didn't want. I've heard of other folks doing that with 1 gallon all grain batches though. The one thing that I am finding helpful is using a refractometer to measure gravity throughout the boil. My next batch, I think I'll crush a bit more finer and start with less water, using sparge water to lower OG instead of DME and boil-off to increase. Not sure this is helpful, just a note to let you know I'm learning with you.

 

[deadwolfbones]

1. Figure out your boil-off rate by boiling a couple gallons of water for an hour.
2. Use the Priceless BIAB calculator to determine starting volumes.

 

[StrangeHaze]

Thank you all for your responses, it's very much appreciated!

@Carolina_Matt The grains were pre-milled, maybe next time I'll select the "extra milled". One day I'll purchase my own mill.
@McKnuckle That's kind of what I thought as well, start at 4gal.
@deadwolfbones Good idea, I'll do that this weekend.

Again, thanks to everyone that responded!

 

[Immocles]

The first few brews are really a lot of trial and error. I had my stovetop biab dialed in and recently switched to a mash&boil. My first brew on that I ended up in a similar situation. Tweak for the next brew day and you’ll hit your stride before you know it.

Once you decide if you’re sticking with the biab process, I’d suggest a simple corona style mill. My mash efficiency leapt noticeably when I started using one as opposed to the pre milled grain. They’re pretty cheap ( I think it was $17 from Walmart), and it’s relatively pain free to manually crank on a smaller grain bill.

 

[bgmac]

Using an online calculator starting at 5.5 gallons and ending with 4 gallons post boil using your exact grain bill at 75% only ends up at 1.033. Yes the extra gallon of water (4 vice 3) would also be a big cause of low OG. But you are still off target even for 4 gallons.

I second the recommendation to mash for 60 minutes and use some sparge water to rinse out those sugars left in the grain. Also, let the bag drip dry the best you can into the boil kettle. Giving it a squeeze like you did can help also.

As others have mentioned, grain crush matters big time with BIAB. I look for a corn meal consistency with lots of flour. If you see lots of dimensional chunks, then it is too course. A mill set about the thickness of a credit card will do the trick with a single pass. Don't stress about damaging the husks. Its a myth that it will release tannins. That only happens with higher temps above 170F during the mash.

 

[Hwk-I-St8]

Poster above says that calculates out to 55% efficiency. FWIW, I BIAB on a stove and do 2.5-3 gallon batches, and I average about 60% efficiency over a dozen or so brews. I tried lots of things: super fine grain crush, squeezing the bag, mash temps, none of it really made a difference. I think for me a lot of it is the amount of wort/trub/hop material I leave in my kettle when I rack it out to a fermenter.

TL;DR - 55% efficiency for BIAB isn't unusual. Use more grain, boil with less water.

TL;DR 2 - what everyone else says, you have way more wort in your fermenter than calculated, so of course your OG will be lower.

This is kind of an interesting point. If your losses (trub, kettle, etc.) remain constant. they become a bigger percentage of your batch when cutting back batch size. This will have a very direct impact on efficiency.

 

[jdauria]

TL;DR - 55% efficiency for BIAB isn't unusual. Use more grain, boil with less water.

Disagree that 55% efficiency is not unusual. Maybe for first timers sure, but I BIAB and get on average 86% mash efficiency and 75% brewhouse. Losses left behind will definitely harm brewhouse efficiency, but if you get a good crush of grain, double crushed ideally, you hit your mash temps and if your pH is in the right range, then you can get mash efficiency up there which in turn will increase brewhouse efficiency.

To the original poster, the fact that your grain was pre-milled is definitely a major factor. Homebrew shops mill at a wide gap to help homebrewers who do a normal AG mash tun/sparge brew day from getting a stuck sparge. With BIAB, no need to worry about stuck sparge and the grain can be crushed almost to a flour, but if crushed that small, then you want a better bag. The ones sold at shops will let a lot of the flour into the kettle. There are sites online that sell better bags. As for using 5.8 gallons of water, I just did a 3 gallon BIAB batch (brew smaller batches inside in winter) and used 5.5 gallons of water for 7 lbs of grain, so you're 5.8 for 4.75 lbs of grain is definitely way too much. What software were you using?

 

[moreb33rplz]

Disagree that 55% efficiency is not unusual. Maybe for first timers sure, but I BIAB and get on average 86% mash efficiency and 75% brewhouse. Losses left behind will definitely harm brewhouse efficiency, but if you get a good crush of grain, double crushed ideally, you hit your mash temps and if your pH is in the right range, then you can get mash efficiency up there which in turn will increase brewhouse efficiency.

To the original poster, the fact that your grain was pre-milled is definitely a major factor. Homebrew shops mill at a wide gap to help homebrewers who do a normal AG mash tun/sparge brew day from getting a stuck sparge. With BIAB, no need to worry about stuck sparge and the grain can be crushed almost to a flour, but if crushed that small, then you want a better bag. The ones sold at shops will let a lot of the flour into the kettle. There are sites online that sell better bags. As for using 5.8 gallons of water, I just did a 3 gallon BIAB batch (brew smaller batches inside in winter) and used 5.5 gallons of water for 7 lbs of grain, so you're 5.8 for 4.75 lbs of grain is definitely way too much. What software were you using?

I've spoken with lots of fellow BIAB'rs in person, and some online, and I have plenty of anecdotal evidence of expereinced brewers getting low efficiency using BIAB. I assure you my crush is not the cause, my mash temp is not the cause, and my pH is not the cause, I measure and have experimented with all 3.

It's the losses for me. I siphon out of my kettle into fermenter, and while its worse with hoppy beers (especially if using whole cone), there is a lot of trub/break in the kettle that forces me to leave a fair amount of wort in the kettle.

 

[bgmac]

I've spoken with lots of fellow BIAB'rs in person, and some online, and I have plenty of anecdotal evidence of expereinced brewers getting low efficiency using BIAB. I assure you my crush is not the cause, my mash temp is not the cause, and my pH is not the cause, I measure and have experimented with all 3.

It's the losses for me. I siphon out of my kettle into fermenter, and while its worse with hoppy beers (especially if using whole cone), there is a lot of trub/break in the kettle that forces me to leave a fair amount of wort in the kettle.

Do you sparge? If not, then give it a try. I bet your numbers will go up. I have never seen efficiency less then 75% after dozens upon dozens of BIAB batches. In the last year, I haven't seen efficiency less then 84% now that I figured out to let the bag drip dry over the BK for a long time after sparge.

 

[soccerdad]

Consider this. 3 vessel brewers often mash for 60 and sparge for 10 to 30. Try a 70 to 90 minute mash. Don't rush. Do a dunk sparge if you need it and let that drain in a colander over a bucket while you heat to boil. My BIAB always gets over 75% mash efficiency. I don't hurry.

 

[McKnuckle]

^
The above is absolutely true. The vanilla 60 minute mash, with or without a fairly quick sparge, is homebrew dogma. It is especially popular now that BIAB and the many all-in-one basket devices are so prevalent. Of course it works, and is convenient, but it's not the end-all if you are seeking to maximize extract yield.

Also, there is occasionally advice on this forum and elsewhere that conversion happens very quickly, so don't bother mashing even that long. If this was really the whole story, then it would not follow that longer mashes produce a higher gravity wort. However, they do, and it is demonstrably provable. Whether this is because starch takes longer to solubilize, conversion itself takes more time, or converted sugar needs more time to rinse from the grain into the free wort, or something else entirely - I don't know. But gravity does increase with a longer mash (and sparge, if practiced).

Similarly, if you are draining your bag quickly and then discarding it, you are reducing your mash and brewhouse efficiencies more than necessary. Follow @soccerdad 's advice and let it drain slowly while you heat to a boil, then return the collected wort to the kettle. Don't rush.

Finally, having predictable efficiency is really about being consistent so you can reliably plan recipes. It's not the end-all of brewing. It's expression as a percentage - like a test score - makes it a metric that brewers obsess over as an indication of their performance. High efficiency in and of itself does not make good beer.

 

[Bobby_M]

A 30 minute mash at 149F is not long enough even if you had an ultra fine crush. At 149 you need about 90 minutes or you can go 149 for 60min and move up to 154F for another 15 minutes. Either way, your mash efficiency was likely the cause.

The crush may have been too coarse as well but without seeing a picture, that's just speculation. Since Morebeer is the source for viking malt, I know for a fact that they crush on the extreme coarse side.

Last... did you squeeze the hell out of the bag? If not, do that.

68 to 75% is pretty typical brewhouse efficiency for me.

 

[moreb33rplz]

Do you sparge? If not, then give it a try. I bet your numbers will go up. I have never seen efficiency less then 75% after dozens upon dozens of BIAB batches. In the last year, I haven't seen efficiency less then 84% now that I figured out to let the bag drip dry over the BK for a long time after sparge.

Yeah I dunk sparge. How much do you leave in the kettle when you go to fermenter?

 

[deadwolfbones]

I'm getting 78-80% efficiency with BIAB and (usually) a 60-75min mash, between 148 and 156F. I have my MM-2 mill set to the typical credit card gap. Easy, consistent.

 

[downzero]

I don't see anything about water chemistry or mash ph, so I'd start there. Calculations of efficiency require precise volume measurements as well, but I agree with others who say that 70% or perhaps even higher is possible with BIAB without anything special. Avoid dough balls and mash for the proper time and at the proper temperature and you will have proper efficiency. I see a light beer recipe above with no acid malt or acid addition, and that is going to be problematic every time. BIAB is great and it is easy to get into all grain by doing so, but it is still all grain brewing and if you're not paying attention to your water chemistry and mash ph you're not going to get ideal results.

 

[StrangeHaze]

I'm surprised by the number of responses, great community here and lots of info for me to take away with.

Not too confident this beer will turn out. Fermentation seems complete after just five days and krausen is just about gone already even though it was very active for the first few days. Did a reading two nights ago and was at 1.010, I'll take another but still plan on waiting a week before bottling, if I decide to. At this point, concerned that it may be infected, I did a taste and it seemed acidic, had a tang on my tongue up front. Other than that, it tasted pretty decent albeit very light and a bit watery. I'll see what the next week brings and maybe bottle anyways with keeping my hopes low. Chalk it up as a learning experience. I was very excited for this recipe, will likely try it again but with many of the adjustments in this thread.

You all have been great!

 

[McKnuckle]

Definitely bottle at least part of it. Very young (green) beer is not super delicious. You should not get any truly rank or foul flavors of course, but beer is always acidic. When it's warm and flat, that's emphasized. Most raw or harsh notes will smooth out over the conditioning period, with carbonation, and with cold temps and settling.

Don't expect huge flavor with the very low OG, of course. So it might end up bland - try again with water volumes corrected!

As for the fermentation time... Yes, primary fermentation is often over in under 5 days. This means the yeast have attenuated the wort as much as they are going to, but the beer is still left alone for a little while longer, so the yeast can metabolize some of the fermentation byproducts and "clean up" the beer.

After that, plan on 2 weeks in the bottle with priming sugar at room temp, then cold conditioning for an additional 2 weeks for peak flavor. Of course you can drink it sooner, and no doubt you will, but those are the typical timing factors for an average strength pale-to-amber colored brew.