Question about yeast and amount of wort

I'm still soaking up info. If I brew a batch less five gallons; maybe two or three gallons. Would I use the same amount of yeast as a five gallon batch or half the amount? If I did use the same amount of yeast as a five gallon batch, and it wasn't necessary how would it affect the fermentation. Thanks guys!

P.S. I think I am having just as much fun collecting info as I will making the beer!

How much do you pitch in the 5 gallons?

It's difficult to over pitch. I'd pitch the same amount.

Shouldn't make any difference. I over-pitch all the time.

All you'll be doing is accelerating the fermentation. People repitch onto existin yeast cakes all the time, and that is enough yeast to do 3-4 batches.

It depends on the style/recipe of beer you are brewing, but it is generally hard to over-pitch. Much better to knowingly put in a bit too much than too little!

If you are using a dried yeast, there is no point in trying to save part of a packet. The yeast dies rapidly once the seal is broken. If you use liquid yeasts without a starter, you're under-pitching regardless.

david_42 said:

If you use liquid yeasts without a starter, you're under-pitching regardless.

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For two or three gallons of wort? Why would you say that?

gotta agree with flyguy, there are liquid yeasts that are supposed to be a pitchable quantity, like Wyeast Activator packs and White Labs vials.

half the reason for making a starter is to make sure the liquid yeast survived all its transportation (especially hot summer months) and to wake the yeast up and get it active, so you don't have lag time in primary.

the other half, of course is to make a massive yeast population.

FlyGuy said:

It depends on the style/recipe of beer you are brewing, but it is generally hard to over-pitch. Much better to knowingly put in a bit too much than too little!

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I was listening to the Jamil Show recently and Chris White, of White Labs, was answering some questions about yeast. He said that it, generally it is better to under pitch than to over pitch, and Jamil agreed. Chris said that you want a lag time of around 6-8 hours, for proper yeast growth and development, and that a short lag time is not necessarily good for the yeast. I found it interesting, but it is generally pretty hard to over pitch. I'm not sure whether I agree or disagree, but he made some good points.

Iordz said:

I was listening to the Jamil Show recently and Chris White, of White Labs, was answering some questions about yeast. He said that it, generally it is better to under pitch than to over pitch, and Jamil agreed. Chris said that you want a lag time of around 6-8 hours, for proper yeast growth and development, and that a short lag time is not necessarily good for the yeast. I found it interesting, but it is generally pretty hard to over pitch. I'm not sure whether I agree or disagree, but he made some good points.

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Yeah, good point. Yet the practical side is over-pitching shouldn't be a big concern for homebrewers because effectively over-pitching is so much harder to do than under-pitching. Under-pitching is easy to accomplish -- especially for brewers who don't want to make up a sufficient starter or multiple packages of yeast, especially when brewing a bigger beer. OTOH, over-pitching is hard to accomplish unless you had your mind set on throwing in a whole bunch of packages of yeast, or making one huge starter inappropriate for the brew.

Of course one notable exception would be re-pitching an entire yeast cake from one batch onto a new one. That is when I would really think carefully about the advice you mention above! Excellent point you bring up!