Half Batches

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Rich71093

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I would like to try an all-grain recipe, but I only have a five gallon brew pot. I have heard of people making smaller batches so I thought of trying a 2.5 gallon batch using the brew-in-a-bag method. I have a few questions.

Can I just split the ingredients in half?

How much yeast? Most recipes don't seem to specify amounts for a five gallon batch, so how much do you use for half a batch?

Does it hurt anything to put 2.5 gallons in a 6.5 gallon bucket to ferment? I don't think the extra air space would hurt anything, but I'm not sure.

Do I just use half the amount of priming sugar or would it be better to use a sugar calculator?
 
id use a sugar calculator. pretty much juch cut all ingredients in half. mr malty should help with the yeast amount. 6.5 g carboy should do fine. smaller im sure would be better. id just not expect many air bubbles with the larger carboy(not that airlock bubbles mean anything) someone chime in if im way off here
 
The grains should be split in half, as well as the hops. Use a single packet of yeast though.

Another option would be to use fermcap-s for boil-over prevention and ferment a bit more. If you use the same amount of grains, you could either just ferment ~4 gallons of brew, or 'top off' to get 5 gallons into the fermenter.

Personally, I wouldn't use a 6.5 gallon fermenter for a 2.5 gallon batch. You should be safe, since the wort would get covered in CO2 pretty quickly. I just think you have more risk than if you used something closer to the right size. If you have CO2 on hand, then you could hit the fermenter with enough to blanket the wort, right before you install the airlock. That SHOULD prevent bad things...

For priming, I would use one of the online calculation tools. I do that for all my batches. Enter the brew temp (at bottling) as well as volume, desired CO2 level, and sugar type. You can round up/down to the closest increment you can measure from there. Just measure by weight.
 
you can still do a full 5gal AG batch with a partial boil and top off after as long as its not a big beer. its not talked about often, but it still works about as well. you may need to adjust your bittering add slightly based on the boil size, but it won't change much. otherwise, yes just cut everything in half (except yeast) and you're good.

you can use this to check how much grain you can fit in your pot: http://www.rackers.org/calcs.shtml
 
Keep in mind that you'll still probably boil off just as much as you would a full batch. Beersmith has a boil off percentage of 9% I believe for almost most brew pots, but really I found if I use the following percentages I get a predictable amount of wort:

10 gallons: 9%
5 gallons: 18%
2.5 gallons: 36%

I did a half batch mash and cut everything in half. I ended up with way less than half because evaporation doesn't get reduced with batch size.
 
Golddiggie said:
The grains should be split in half, as well as the hops. Use a single packet of yeast though.

Another option would be to use fermcap-s for boil-over prevention and ferment a bit more. If you use the same amount of grains, you could either just ferment ~4 gallons of brew, or 'top off' to get 5 gallons into the fermenter.

Personally, I wouldn't use a 6.5 gallon fermenter for a 2.5 gallon batch. You should be safe, since the wort would get covered in CO2 pretty quickly. I just think you have more risk than if you used something closer to the right size. If you have CO2 on hand, then you could hit the fermenter with enough to blanket the wort, right before you install the airlock. That SHOULD prevent bad things...

For priming, I would use one of the online calculation tools. I do that for all my batches. Enter the brew temp (at bottling) as well as volume, desired CO2 level, and sugar type. You can round up/down to the closest increment you can measure from there. Just measure by weight.
Click to expand...

+1 the only thing I would add is if you are doing a half batch, you can use liquid yeast, pitch the whole thing - no starter required :)
 
Hi,

Right now I only BIAB in a 20 quart pot. I start with 4 gallons of water and just cut everything in half except the yeast (no starter). I tried mashing in a separate 8 quart pot then batch sparging but discovered I could get efficiency in the low seventies without the hassle.

I was suprized that fermentation is generally about 25% quicker than my 5 old gal batches. I downsized my fermenter to a screw-top 5 gal bucket and use a 2 x 3 gal PET secondaries.
 
Definitely use Beersmith or some other software to show you how much to add of each ingredient.

But really, and I say this from experience, it pays off to just get a bigger pot and do a full batch. I had a 5G pot as my main pot, did my first all grain in it and got a whopping 2.5G out of it. I'm so stingy with that beer and it went so fast, half of it was gone before it actually got to age properly.

Unless you're made of patience and can let a beer sit for 4 weeks without drinking it, then half batches are a once in a blue moon thing :)

But yeah, I fermented mine in a 6.5G bucket, 2.5 filled with wort, and no issues. Cept it was harder to take a sample. Nothing else really was different, same time to brew it, about the same time to bottle (few minutes less maybe). I pitched half my normal yeast and it came out fine.
 
I brewed 5 gals of a belgian IPA as BIAB with 12 lbs grain in a 34 qt (6 gal) pot at ~1.25 qt water / lb grain. The online calculator above suggests 4.75 gallons of mash water; so i used that plus 1.5 gal sparge water. Because the grains soaked up ~ 1 gallon, after i added the sparge to the boil pot I had almost exactly 5 gals for the boil.
Basically, I'd recommend using the calculator and squeeze as much as possible into that pot.
As a rule my beers always have anABV of 5.5+. My OG was 1075; big beers CAN be done as BIAB!
 
dcp27 said:
you can still do a full 5gal AG batch with a partial boil and top off after as long as its not a big beer. its not talked about often, but it still works about as well. you may need to adjust your bittering add slightly based on the boil size, but it won't change much. otherwise, yes just cut everything in half (except yeast) and you're good.

you can use this to check how much grain you can fit in your pot: http://www.rackers.org/calcs.shtml
Click to expand...

So your saying to treat it like an extract brew and boil 2.5 gallons of concentrated wort and then add the other 2.5 gallons to the fermentor? I don't see why that wouldn't work. I agree with you guys saying that it is the same amount of work for half the beer, but my pot is 5 gal and I don't think my stove will boil 5 gal even if I had a bigger pot.
 

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