Not sure if this is more of a yeast or general brewing question but...

[deadboy]

OK, getting started brewing bigger batches. Going from standard 5 gallon to 10 or 15 gallon batches. My question is this:

Do I need more yeast? I generally use an appropriate Wyeast pack. But to my line of thinking as long as the yeast is there it will continue to multiply until the "food" runs out. So do I need to double/triple the yeast or is a normal amount of yeast acceptable? If I was to not adjust the amount of yeast would I just need to increase the time in the primary?

 

[duboman]

Go to yeastcalc. Com and plug the numbers in based on your new batch size but in short, yes you will need to pitch a great volume of yeast because if the great volume of wort.

Liquid yeast packs, even though they state they are, are generally not an adequate amount to pitch for a standard 5g batch at 1.040 or so.

If you severely under pitch your larger batches you really risk the quality of your beer and stress out the yeast.

 

[igotsand]

I do 15-20 gallon batches at a time..
U need to pitch a lot!!
I'll normally get 2 yeast vials and do a 2000ml step starter for my batches...it works well and I'm saving some money too....
I only stress 1type of yeast for underpitching, and that's the wlp300...I love that banana smell!!

 

[deadboy]

Cool. thanks for the info.

 

[Denny]

If yeast continued to multiply until the food ran out, yopu could get by with only pitching one yeast cell. We all know that wouldn't work very well. You wantm to limit the yeast reproduction to just a few generations, which is why you piitch more yeast.