Divining Fermentation Time

[BlackHat]

I'm new enough to homebrewing to only be on my second batch. I've done my first two batches from Northern Brewer ingredient kits and I have been fermenting according to the times they list for the kit. For example, 3 weeks fermenting and 3 weeks bottle conditioning for kits listed as 6 weeks.

I want to try something other than a kit for my next batch, so I've been looking up recipes online. One thing I'm not seeing with them are solid fermentation/bottling times. I was told that a batch is ready for bottling when the gravity reading doesn't change for 3 days. However, I would like to know generally how long fermentation will take just by reading the recipe.

... Is this even possible?

 

[Yooper]

Well, there are some loose guidelines I follow for timing my beer. The first is the famous 1-2-3 guideline. This means 1 week in the primary fermenter, 2 weeks in the clearing tank and 3 weeks in bottles before drinking. Usually though, it's more like 10 days in the primary and then 10 days to three weeks in the clearing carboy until I get a chance to brew. It's important to note that any "rule" is really overruled by the fermentation. Each is a bit different, depending on temperature, yeast health, type of yeast, etc.

The best guideline is to leave it in the fermenter until it's done. It's done when you get the same reasonable fg 3 days in a row. Usually you can expect 70-75% attenuation of most yeasts, so that's the area of fg you'd be looking for. For example, if your og was 1.060, you'd expect a fg in the neighborhood of 1.014 but that isn't written in stone because there are some variables. After you reach that fg, you can rack to the clearing tank for as long as you want. If you are only doing one stage brewing in the primary fermenter, I'd suggest leaving it at least two weeks in the fermenter, regardless of the fg readings.

There is nothing to be gained by rushing to bottle, since after fermentation is finished the yeast get busy cleaning up after themselves, eating their own waste products and the beer clears up a bit.

So, if you read the recipe, look at the og and you can calculate the expected fg. Some beers have some unfermentable things in them, but for the most part you can make an educated guess. Or you can use some brewing software and that helps alot!

 

[Benny Blanco]

Suppose your OG is 1.060 and you get a consistent FG of 1.030, is there anything you can do if your fermentation is incomplete?

 

[Yooper]

Yes, if you have a stuck fermentation, you can always pitch more viable yeast.

 

[Benny Blanco]

If you did have a stuck fermentation and you pitched more yeast, would you have to aerate the wort again? What if you use a different brand/strain of yeast?

 

[Yooper]

No, no aeration. You want to quietly do it, no splashing. You can make a yeast starter and aerate that to get the yeast going, but not the beer.

Same yeast or different, really doesn't matter. I'd try to use the same if I had it.