Brewing small AG experimental batches in 5 gallon setup

[djsereno91]

I've been contemplating doing some experimental batches. At the moment I'm planning on experimenting with some coffee IPAs but I am curious about scaling down batches in general.

Currently I have an all grain setup (water cooler style) for 5 gallon batches. When doing experimental batches, say 1 gallon, 2.5 gallon, can I simply scale down a recipe while using the same equipment? I'm thinking I could scale down the ingredients proportionally, but probably not the water since my boil off rate is the same. I am concerned however about how the smaller batch would work in a cooler made for 5 gal batches. The volume of the grain bed will be smaller, but the diameter of the cooler remains the same. Will this pose an issue?

 

[leonardoreges]

You'll need to scale down your water as well and then compensate your boil off rate.
The size of your equipment might be an issue, as long as a to thin grain bed causes efficiency loss.

 

[pricelessbrewing]

Grains scale linearly with respect to batch size, and brewhouse efficiency. At least close to linear that the difference is minor.

Hops for flavor, dry hop, whirlpool, flameout, and aroma additions scale linearly with batch size.

You will then need to adjust hop additions to get your desired bitterness.

You will need to perform your own water volume and temperature calculations based on the recipe and your equipment, this is a non-linear formula so it doesn't scale as such.

 

[RM-MN]

You'll probably be OK with the cooler you have for doing 2 1/2 gallon batches but you will want to think of another way to do 1 gallon as you will likely lose too much heat in the cooler with such small volume.

 

[McKnuckle]

^This is correct, and is pretty much the only issue.

I use a 5 gallon cooler mash tun and brew 2.75-3.25 gallons of beer. I end up with somewhere around 2.7 gallons of volume in the cooler during mashing, and also during the batch sparge. I employ a mash cap made of insulated material, and I zip up the cooler in a winter coat, but I still lose 2 degrees F every 30 minutes, give or take.

It's totally workable. But the less volume, the more heat loss, so you need to factor that in.

 

[pursuit0fhoppiness]

I recently just went all-grain and bought a 5 gallon picnic cooler mash tun as I'll be doing 2.5/3 gallon batches. My first 2.5 gal batch is currently fermenting, in my 6 gallon bucket fermenter that I used for 5 gallon extract batches. I still had airlock bubbling a day in (way to go yeasties!), but was wondering if all that extra headspace will have an effect. If airlock was bubbling does that mean CO2 purged all the O2 out? (I will be opening it once for dry hopping and once for FG)

 

[pricelessbrewing]

No need to worry about headspace during primary fermentation, only if you're going to be aging the beer.

Re: c02 purge

Kinda but there's still some oxygen present, iso it's not all the way purged. That's assuming a good bucket seal, it's not uncommon for buckets to leak, which will bring the bucket back to atmosphere after fermentation slow down, or if you open it at all it will return to containing a good portion of air (read: oxygen).