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Gravity and yeast

At what gravity point does a batch of wort need more than 1 packet of dry yeast? For example, 6 lbs. DME, 1/2 lb. Dark Belgium Candi sugar, 1/2lb. cane sugar. I understand it’s normal to make a starter using dry yeast, but when should I consider using 2 yeast packets? Using US-05.

No, it’s not normal to make a starter for dry yeast and it can in fact be detrimental. I’d go to more than one pack if the OG is over 1.070. Assuming that’s a 5 gal. batch, you should come in around 1.064, so one pack is fine.


To go a little further than @denny dry yeast is packaged with nutrients to assist in fermentation. If you make a starter you’ll use up the nutrients, thus depleting them for fermentation.

In addition, it’s likely cheaper, or at least close, to buy an additional packet of yeast rather than DME for the starter.


Hydrate if you want… just to sprinkle on the top of your fresh, cooled wort is all good… Sneezles61


I started using oxygen a couple years ago and always seem to have a strong vigorous fermentation.

I just brewed an imperial brown ale last night, got done with pitching and cleanup at about 11pm. Pitched 1 pack of S-04 into 4 gallons of 1.099 OG wort. As of 7:00am this morning, there is already 1/4 inch krausen and it’s bubbling away. EDIT: And no rehydration, either. I just sprinkle the yeast on top. Didn’t aerate, didn’t mix it in, just sprinkled and went to bed.

Dry yeast packets contain double the viable yeast from liquid yeast packs, and dry yeast also has the advantage of lasting pretty much forever in refrigeration. I only recommend using 1/2 pack dry yeast for 5 gallons under most circumstances, unless brewing a lager or a really strong ale as I have above, then use the whole pack.

For liquid yeast, it’s usually best to make a starter, but I still only use 1 pack, unless I were to brew 10-15 gallons or more, then I might use 2 or 3. Otherwise 1 is good. The stronger the beer, the bigger the starter, or if brewing a lager then make a bigger starter.

You can use to calculate things as well, but I always slide the bar all the way towards minimum packages, and round everything way down as he’s overly conservative. Ignore his advice when using dry yeast.

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I stopped using oxygen or aeration many years ago in favor of pitching a good quantity of healthy yeast. If you do that, oxygenation/aeration becomes much less necessary to the point where you can usually skip it.

So, @denny you just transfer the wort into the bucket, add the yeast, and you’re done? No shaking? No stir-stick? No double-mesh strainer? Nothing? Is there any increased lag time?

Under what conditions would you choose not skip it?

If I knew I was underpitching or my yeast wasn’t in good shape I would make sure to aerate.

Denny makes a good point. The purpose of aerating is to allow the yeast to efficiently multiply. With a big pitch, there is less need for that. So the question of how much to aerate depends on the quality and quantity of your pitch.

Then again, I inadvertently did an experiment relating to this some years ago. I discovered that if I didn’t aerate before pitching very healthy yeast (in this case plenty of dry yeast), the fermentation went great, but the yeast I tried to harvest from the batch was in poor shape for the next pitch, and that beer had a slow fermentation with reduced attenuation.

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So would you recommend adding, “if you intend to repitch” as one of the reasons to aerate?

I usually still aerate with a stone and a $10 O2 tank that lasts a couple years; it’s more out of habit than any science-based reasoning though.

Not necessarily. I repitch and don’t aerate.

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