Back to Shopping at

2.5 gallon batch pitch rate?

New to the forum. Yesterday I brewed a 2.5 gallon batch of an Imperial Stout OG 1.083. I pitched it with the entire contents of a fully swelled WYEAST 1056 smack pack. Fermentation began within just a few hours and air lock bubbled better than once a second for 24 hours and now, no more bubbling. Is it ok to pitch the whole pack for a high gravity 2.5 gallon batch? If not what would be the best way to pitch a half batch? I know the beer is still fermenting however, what if any are the effects of such a change in air release? If I haven’t met my final gravity by the end of the week should I repitch or siphon to a secondary/potentially repitch at this point? More or less looking for advice as to how to properly pitch for high gravity 2.5 gallon batches. Thanks, great forum.

You may have slightly under pitched, but not by very much. Here is a good calculator to use for pitch rate and making starters. ... alculator/

Two weeks after the active fermentation began take your first specific gravity reading. Take another reading two days later. If they are the same final gravity has been reached, but the yeast are not finished yet. After fermentation is complete the yeast start cleaning up off flavors produced by the fermentation. Another week and this process may be completed and the yeast and other sediments will begin to settle out.

Your beer will benefit by being left in the primary. High gravity beers like this take time to develop.

Don’t forget to drink your gravity samples. Gives you a good idea of how your brew is progressing and what flat green beer tastes like.

Awesome thanks for the quick reply. The only thing that confuses me at times when using a pitch rate calculator is that I dot fully understand the target pitch rate calculation (.35, .5, 1, etc) could you explain this a bit? Also since I pitched a full, 5 gallon recommended smack pack into a 2.5 gallon batch and you’re concern is potential under pitching, would you recommend a starter for next time? If after 2 weeks and multiple gravity readings my final gravity is not where I want it to be should I rack to secondary and repitch?

I let the Brewers Friend calculator do all the work for pitch rate. I brew most of my beers from kits which give me the estimated OG. I enter the estimated OG into the calculator, the yeast production date, and select Pro brewer 0.75 (ale) for the pitch rate. I use this pitch rate just because it is the same pitch rate YeastCalc calculated and always had good fermentations meeting the estimated final gravities for the yeast used. YeastCalc is no longer available.

On the Brewers Friend yeast calculator page there is a link to an explanation of target pitch rates.

I would recommend a starter next time. In Brewers Friend calculator I entered 1.083 as OG, the yeast production date as the date of your post, and Pro brewer 1.0 as the pitch rate. BF calculated an underpitch of 89 billion cells.

If your OG gets stuck high there will be no benefit in racking to a secondary vessel. Now that fermentation has slowed let the wort warm to ambient room temperature. This will encourage the yeast to stay in suspension and work longer.

If you do have a stuck fermentation after your beer is in the primary for two weeks post the results in this same thread. I have never had to work with a stuck fermentation. Will have to get help from brewers with experience.

I hope you can post back your hydrometer readings are spot on for desired FG.

I think you can estimate the yeast by basically taking the volumes and assuming 1/3 for ales and 1/2 for lagers on the re-pitches, as long as you are repitching within the first month and not storing the yeast for a significantly greater time.

I think it would be helpful to explain why you pitch what you pitch.

The generally accepted goal for pitching is 0.75 million healthy cells per milliliter per degree Plato for ales, 1.5 million for lagers.

So keeping everything else constant if you halve your volume you should halve your pitch rate. But if you double your gravity, you need to double your pitch rate. You made a half sized batch of double strength wort, so a full smack pack should be about right as long as the yeast was healthy and it contained the right amount of yeast. If you run the calculations, you’ll find that the smack packs only contain about half the yeast cells needed for an average-strength 5 gallon batch of ale.

In general, yeast is only at full health for a few weeks after it is put into the smack pack. The older it gets, the more cells die and the less healthy the remaining ones are. So it is almost always beneficial to make a starter, as that ensures healthy yeast and allows you to build up the population to the recommended level.

Back to Shopping at