Fermentation and Yeast for Small Batches (2.5 gallon)

[brian_n]

I just got a 3 gallon carboy that I plan on using to make some 2.5 gallon batches of either experimental beers or high gravity beers. I've only made 5 gallon, non-high gravity beers over the last few years, so I have a couple questions:

1) For 5 gallon batches, I usually use a traditional 6+ gallon plastic bucket primary for 10ish days and then a 5+ gallon glass carboy secondary for 10-15 days before bottling. I'm okay to still use the plastic bucket primary for 2.5 gallon batches right? From what I understand about oxygen and beer, it doesn't matter until fermentation begins, at which point the fermentation will fill the plastic bucket with CO2 regardless of size. Right?

2) If I'm making a normal beer (OG of ~1.050) should I just pitch the entire yeast packet (I use dry or liquid depending on the beer)? Or, if I were to pitch approximately half the yeast packet, what would you advise doing with the non-pitched yeast in order to use it on future batches?

3) If I'm making a high gravity beer (OG of ~1.080) that calls for a big starter or 2 packets of yeast for a normal 5 gallon batch, I should be okay using just one packet on a 2.5 gallon batch, right?

 

[blackstrat5]

Use a pitching calculator like www.mrmalty.com. The amount of yeast pitched depends on viability of the yeast, gravity of wort and the volume. The viability is estimated from the age of the yeast your using.

Yes the yeast will produce CO2 that will fill the bucket. Its more dense so it'll sit over the surface of the beer.

 

[brian_n]

Thanks for the info. That answers all of my questions except what, if anything, to do with the excess yeast. I know I can pitch it all, clean it, create a starter in future, etc..., but it seems like it would be easier to only use the necessary amount of yeast, and save the rest in a sanitized bottle (for liquid yeast). Anybody ever done this?

 

[ReverseApacheMaster]

I do a lot of small batches. I think you'll find that washing yeast will help lower your brewing costs but you may not want to do that.

You could probably be fine saving part of the dry yeast packet but I seem to recall with the dry yeast that after it gets exposed to oxygen it has a shorter shelf life but I may be wrong. With either dry or liquid yeast you could pitch just what you need (or even take a slant and build that up) and save the rest. I don't know how you would measure the right amount like that but you might be able to. If you're going to store the yeast you need to store them in a sanitized bottle with boiled water (no distilled water). Similar to any other yeast in that condition, it will only stay good for so long before the yeast cells start to die off.

 

[Brizzo]

i have been doing smaller batches lately from 1 to 2.5 gallons and have been experimenting with yeasts and other things. I previously did a 1 gallon batch of beer and used about 5 grams from an 11 gram dry yeast packet and had great results. The beer was a basic single hop ale and I used carbtabs to carbonate the bottles.

This past Sunday I made a 5 gallon batch of a brown ale and split the batch between two carboys, one was 5 gallons and the other is 6.5. In one carboy I pitched a one quart starter of Danstar Windsor dry ale yeast and in the other I pitched a 1 pint starter of S-05 dry yeast. The S-05 was left over from the 1 gallon batch and I wanted a starter just to ensure viability of the yeast.

I made a larger starter with the Windsor because I know that is usually leaves a higher final gravity and I was hoping that maybe pitching more will help be get that final gravity lower.

Both carboys were bubbling like crazy within an hour and the windsor had bubbles being pushed out like 2 per second. The Windsor peaked and the krausen had fallen back into the beer within 24 hours. The S-05 had a 1 inch foam on top of it within 24 hours and today -2 days later- has about a 8 inch layer on top. It is still bubbling in the airlock and the windsor appears to have stopped.

I realize I probably pitched WAY to much yeast in both beers but I guess we will see how my experiment turns out.