Fermentation time for lagers.

[HunterBK21]

Hi everyone, I'm new here, and relatively new to homebrewing. This is my first brew so I just have a quick question about weather my beer is taking too long to ferment and should I pitch more yeast or not. I know how annoying it is to have someone ask you a question and not give you any details, so I will try my best.

I started brewing a 40 pint Tom Caxton lager kit (1.8Kg), I didn't want to spend too much money when I ran the risk of the brew being a failure so I added 1kg of dextrose instead of using DME (It's quite expensive here).
My hydrometer reading on brewing day showed this:
Specific gravity = 1.034
Potential Alcohol = 5.5%
Dissolved sugars = 95g/l

That was on the 20/1/08, so 31 days ago today, and my hydrometer reading today showed:
Specific gravity = 1.015
Potential Alcohol = ~3%
Dissolved sugars = 45g/l
This shows it has only just gone past the halfway stage. There is still visible fermentation, although it is minimal, and there is only a small amount of foam (The name escapes me for now) left ontop of the beer. The temperature where the fermenter is has been relatively stable at around 3-6C, but has recently started to get has high as 8-10C.
The books I have on home brewing; Homebrewing for Dummies, and The Joy of Homebrewing have little to say on the subject of how long it takes a lager to ferment, only that it "Takes a bit longer", So here is the only place I have left to go to.
So if someone could please advise me as to what to do with my brew, that would be great. Thanks.


P.s. Sorry for the long-winded post, but I didn't want my first post to be regarded as bad for not providing enough information.

 

[Padstack31]

I normally stop fermenting my beers when I don't see the airlock bubble at least once a minute...

Do you know what your OG target was, 1.031 seems a bit low to me which make me think that you didn't have enough sugar in your wort to begin with. Also, because you used dextrose and not DME that may have somthing to do with it. I know that the different surgars ferment differently but I don't know the details. A final OG around 1.01 to 1.02 is pretty common.

No worries though, if the airlock is only bubbling every other minute, then I would bottle this bad boy and let is start carbonating...31 days should be plenty of time to finish ferementation and you just may end up with a small beer.

 

[Padstack31]

Oh, and the foam is called "krausen'

 

[HunterBK21]

My hydrometer has "Start beer" and "Bottle beer" markings on it. When I started it the reading was just inside the "Start beer" area, but the level is still a bit outside the "bottle beer" area. I have always found with items such as hydrometers etc. that the markings can be a bit off. Im just wondering should I leave the fermentation go at this pace, bottle it now, or pitch more yeast.

Thanks, I knew it started with a K.

 

[Padstack31]

Hydrometers are also calculated for specific temperatures, which may explain why you are thinking your readings are a bit off. I know mine has take temperature readings as well as specific gravity so that I can easily convert the number.

I would recommend bottling it if you think the fermentation has slowed down. If it is bubbling at all, then the yeast is still alive and eating the sugar, there just isn't anything a lot left for them to eat. Before long, all the fermentable sugars will get converted and their won't be anything left for carbonations...from what I know, I say you bottle it.

 

[HunterBK21]

Hydrometers are also calculated for specific temperatures, which may explain why you are thinking your readings are a bit off.

I never thought of that, I'll do another reading tomorrow, but leave the sample warm to 20C before I take the reading.

 

[Yooper]

I'm not sure what sg you are expecting for your beer to finish at- it's really a function of so many variables, like fermentables, temperature, and yeast. Most yeast will ferment to about 75% attenuation, which would mean you're trying to get to around 1.008 or so. That seems very low to me- so I wouldn't be surprised if you don't make it to the "finish" line.

Airlock activity is not a reliable indicator of fermentation progress, so make sure you use your hydrometer as a guide.

A good way to know if the beer has finished fermenting is to take successive SG readings daily at the end of fermentation. When it has been the same 3 days in a row, it's usually ready to bottle.

What kind of lager yeast did you use? That would really help us to figure what's going on.

 

[boo boo]

If your OG is correct than I'm afraid you'll not get the 5.5% ABV out of your lager. Most lagers are fermented at about 8 to 10c so 3 to 6c is a bit low, and could delay the finish of your brew by a week or so. You don't say what yeast you used, so I'm going to assume you pitched a healthy amount of actual lager yeast.
Now comes the hard part. Lagers DO take quite a bit longer to finish, so don't go bottling it until you are absolutly sure it has finished fermenting.

My average lager starts life in 500 ML flask as a yeast culture and goes to a gallon jug to finish the first part. ( I use liquid yeast and so need to boost my cell count to have enough yeast to do the job by doing a starter ) It is then cooled down below the temperture I plan on pitching it at and the spent wort on top is decanted. On brewday I do my recipie and cool it to fermenting temps which in my case is 10C. Pitch the yeast into well oxygenated wort and about 24 hours later I start to see krausen forming. I leave it in primary at a constant temp of 10C until the foam cover starts to break and then I let my temps rise to 15C for a diacetyl rest. After all fermentation signs are finished, I leave it for another 3 to 4 days and then rack into a secondary/clearing carboy to start my lagering peroid, which usually lasts at least 1 to 2 months at 2C.
At this point I keg my Beer.

Lagering takes a bit of patience to do right, but it isn't rocket science.

To sum up a bit, in your case let your brew warm up to restart active fermentation so it can finish at the proper gravity.

Good luck!

 

[malkore]

I would recommend bottling it if you think the fermentation has slowed down. If it is bubbling at all, then the yeast is still alive and eating the sugar, there just isn't anything a lot left for them to eat. Before long, all the fermentable sugars will get converted and their won't be anything left for carbonations...from what I know, I say you bottle it.

Sorry, but there is bad info here that needs to be corrected.

You do NOT bottle when fermentation slows down. you bottle when fermentation has COMPLETELY HALTED and you're at (or near) the expected final gravity for the recipe.

You DO WANT all the fermentable sugar to be consumed by the yeast during primary.

Bottles are carbonated because you ADD MORE SUGAR at bottling time (usually 4oz - 6oz of dextrose, depending on the beer style).

Bottling when fermentation is still active is an ideal way to make bottles that gush half the beer out as soon as you open it, or worse, bottles that start exploding in your closet.

 

[HunterBK21]

I don't know what strain of yeast I used. It was the one that came with the kit. I have only found 2 homebrewing shops in this country so far, so my choice of yeast is extremely limited (I can get beer, cider, white wine, or red wine yeast) so I can't really replace the yeast in the kit with a better one.

 

[Yooper]

Well, I guess the best advice I can give is just to wait until the hydrometer readings don't change at all over the course of 3-4 days. Then it would be safe to bottle, I assume. I'd do what Boo Boo suggested, though, and warm it up to 10 C or so those last few days, just so it doesn't restart after you bottle it.