About 3 weeks ago I brewed my very first beer, a simple lager. I checked on the beer after 1 week of fermentation and now again after a bit over 3 weeks. At both times the density of the beer didn't really change. I think that no fermentation took place but I am not sure how to tell. Here is a photo of the beer https://i.sstatic.net/jhANr.jpg, is this green edge above the beer normal?

I used about 7g of dry Safbrew T-58 yeast for roughly 5l and I still have about 6g left. The temperature of the room is about 15-19 degrees and it's quite dark.

Can I still activate the yeast or should I add some yeast? Is there any way to save the beer?

  • What were the gravity readings you took? For a "simple lager", I'd imagine an initial gravity reading around 1.050 and a final gravity reading around 1.010.
    – jsled
    Commented Mar 13, 2016 at 14:18
  • Initial reading was 1.040 and after 3 weeks it is now about 1.034. Commented Mar 13, 2016 at 14:27
  • Did you rehydrate the yeast before you pitched or just sprinkle it on top? Rehydrating isn't strictly necessary, but can help.
    – TMN
    Commented Mar 14, 2016 at 16:18
  • Is this an answer or a comment?
    – brewchez
    Commented Mar 14, 2016 at 17:03

2 Answers 2


First, I strongly agree with the comments made in this thread. Triple-check your gravity readings, and test against water (should report 1). Many (most?) hydrometers are calibrated for 16 C, so you'll likely need to make temperature corrections - refer to the hydrometer's manual on how to do this.

Secondly, you call it a "lager" but T-58 is an ale yeast. 15-19 C is a tad chilly, I would say. Get it up to 20-21 - that's still not quite warm enough to have to worry about esters or diacetyl.

Third, you mention you think fermentation took place by you are "not sure how to tell". Did the airlock bubble profusely for a few days? Did a foam (krauesen) form on the top of the beer? If yes, then your yeast has done it's business and fermentation is complete.

Lastly, You can always add more yeast - it wont hurt. Get those temps up, and let it sit for another week. Then, secondary to get things off the yeast cake.


Gratz on your first brew!

From the picture. It appears that it hit high krauesen and left behind hop material. (green stuff)

Re-check gravities Confirm your OG and FG for accuracy. Temperature of the beer is important, check you hydrometer instructions for temp adjustments.

If it's underattenuated so far. Swirl the yeast up a little and, Let it warm up to 70°F. If it gets active again you can then slowly start largering it for a couple more weeks. Or add fresh yeast.

PS: It is remotely possible the green could be algae. I've seen it happen. But unlikely at lager temps without light. If you swab it and smear on a white paper you can tell if it's hops or algae. Algae will smell musty, hops like hops. Algae will smear like paint, hops you will see small leaf flakes with a magnifying glass.

  • Just to add something: Test your hydrometer. Maybe the beer is done, but your hydrometer is broken. Commented Mar 15, 2016 at 4:51
  • 1
    @AtronSeige I can't figure out a way a hydrometer can fail and give a higher gravity reading. A crack would make it less bouyant, losing vacuum, giving lower gravity readings. I guess maybe if a chip of glass flaked off or if the scale somehow moved it could read higher gravities. Commented Mar 15, 2016 at 14:02
  • Temp can also cause it to read different things. I just think it is a simple thing to test and cross a possibility off the list. Water at 20C should read close to 1. If not, then you know where (at least one) problem is. Commented Mar 16, 2016 at 6:31

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