Hello.
I brewed a Marzen about a month ago, and the airlock just started bubbling again after 3 weeks of inactivity. I’ve been brewing for about four years now, but I’ve never had this happen before. My first thought is an infection. But the aroma is clean and there’s relatively vigorous bubbling, so it’s hard to be sure.
Smelling it, I’m getting raw dough / yeast, a little bit of toasted malt, and some fruit. The smell is about the same as it was during primary.
I pitched about 8 oz of 34/70 slurry I saved from a Czech Pils (about 2 months old). Primary started strong after ~36 hours. There was almost no airlock activity about 48 hours after primary started. The gravity was at 1.016 after two weeks in primary at around 70-72 F. After I got that reading I swirled the fermentor to resuspend the yeast twice in two days. I didn’t see much activity after that. Now, two weeks later, it’s fermenting again.
If anyone has any thoughts on why this is happening, or has experienced this before, I’d be grateful to hear.
Thanks,
Ben A.
P.S. - I’ve included the recipe below
Brew Method: All Grain - Style Name: Märzen - Boil Time: 60 min - Batch Size: 20.8 liters (fermentor volume) - Boil Size: 24.6 liters - Boil Gravity: 1.050 - Efficiency: 82% (brew house) - Hop Utilization Multiplier: 0.8
STATS:
Actual Original Gravity: 1.059
Target Final Gravity: 1.011
ABV (standard): 6.4%
IBU (tinseth): 22.27
SRM (morey): 9.49
Calculated Mash pH: 5.18
FERMENTABLES:
1.7 kg - Stone Path Pilsner (36.2%)
1.25 kg - Briess Bonlander Munich (26.6%)
1.25 kg - Stone Path Nor’East Munich (26.6%)
0.5 kg - Briess Victory (10.6%)
HOPS:
50 g - Tettnanger, Type: Pellet, AA: 3.9, Use: First Wort, IBU: 20.89
6 g - Tettnanger, Type: Pellet, AA: 3.9, Use: Boil for 20 min, IBU: 1.38
MASH GUIDELINES:
- Infusion, Temp: 68 C, Time: 60 min, Amount: 28.51 L
OTHER INGREDIENTS:
7 g - Gypsum, Time: 0 min, Type: Water Agt, Use: Mash
5 ml - Lactic acid, Time: 0 min, Type: Water Agt, Use: Mash
YEAST:
Fermentis / Safale - Saflager - German Lager Yeast W-34/70
TARGET WATER PROFILE:
Ca2: 94.1 Mg2: 8 Na: 40 Cl: 176 SO4: 184 HCO3: 0.7