Brewing Small.

How, using a 5 gallon recipe, would I determine how much yeast is necessary for a 2.5 gallon brew? I am trying to cut 5 gallon recipes in half in an effort to experiment with different brew recipes and adjuncts without committing to a full five gallon experimental beer.

Thanks, in advance, for the help!

i'd use dry yeast, if possible, so you could use 1/2 a pack. otherwise, if you use liquid yeast, try to do 2 2.5's at the same time that use the same yeast. liquid yeast doesn't do so good after opening and sitting unless you use harvesting techniques

There are some online calculators that will tell you pitching rates with batch size as a variable. I use this one:

http://www.mrmalty.com/calc/calc.html

Great, thanks for the responses!

I will definitely be using the link provided.

Also, I considered using the "half-pack" idea, so I'm glad to see someone else suggest it. I'll be using that for sure.

Were you drinking before you tried the math?

I've been brewing 2.5 gallon batches all summer, going by the mr.malty numbers in general one full smack pack has been perfect for most of my batches, even had to make a starter for a couple.

Since the required amount is usually about 750000 yeast cells per ml times gravity points it ends up being close to the 100 billion cells in a smack pack for anything over 1.050 or so.

I brew 3g batches, and I generally use half a dry yeast packet or one whole smack pack.
If I'm making a huge stout (9-11%) I use a whole dry packet or even two smack packs. For that, it would makes more sense to make a starter.
I love small batches: easy to clean up, easy to lift the fermenter ( I'm a weakling), bottling only 24 12oz. Bottles.
A problem has arisen with my Zombie Dust clone. There just isn't enough, and I think it may be time to brew a full five gallons. It is awesome beer.

Pitch half a smack pack, and make a starter with the other half for your next batch. Or just pitch one full packet of dry yeast without rehydating it.

wiggybrewer said:

Pitch half a smack pack, and make a starter with the other half for your next batch. Or just pitch one full packet of dry yeast without rehydating it.

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No. Why would you pitch half a package of liquid yeast but an entire package of dry yeast when an entire package of liquid yeast has a lower cell count than a package of dry yeast?

Check mrmalty.com. I suspect you'll find that an entire package of liquid yeast is about right for a 2.5 gallon batch.

downtown3641 said:

No. Why would you pitch half a package of liquid yeast but an entire package of dry yeast when an entire package of liquid yeast has a lower cell count than a package of dry yeast?

Check mrmalty.com. I suspect you'll find that an entire package of liquid yeast is about right for a 2.5 gallon batch.

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This is correct.

Here is a Gumballhead Clone recipe I built from many recipes found on HBT and other places on the web. It is for 3 gallons. I'll let you know how it goes.

Recipe: Gumballhead Clone
Style: American Wheat or Rye Beer
TYPE: All Grain
Boil Size: 4.90 gal
Post Boil Volume: 3.90 gal
Batch Size (fermenter): 3.25 gal
Bottling Volume: 3.25 gal
Estimated OG: 1.055 SG
Estimated Color: 5.8 SRM
Estimated IBU: 28.1 IBUs
Brewhouse Efficiency: 75.00 %
Est Mash Efficiency: 86.5 %
Boil Time: 60 Minutes

3.25 lb Wheat - Red Malt (2.3 SRM) 50.0%
2.75 lb Pale Ale Malt 2-Row (3.5 SRM) 42.3%
0.50 lb Aromatic Malt (20.0 SRM) 7.7%
0.25 oz Amarillo Gold [8.50 %] - First Wort 20.0 7.7 IBUs
0.25 oz Amarillo Gold [8.50 %] - Boil 60.0 min 11.5 IBUs
0.25 oz Amarillo Gold [8.50 %] - Boil 15.0 min 5.7 IBUs
0.25 oz Amarillo Gold [8.50 %] - Boil 5.0 min 2.3 IBUs
0.50 oz Amarillo Gold [8.50 %] - Boil 1.0 min 1.0 IBUs
London ESB Ale Wyeast Labs #1968
0.50 oz Amarillo Gold [8.50 %] - Dry Hop 7.0 Day 0.0 IBUs
Mash 152F