First Lager Fermentation Question

I brewed a 13 gallon batch of Vienna Lager yesterday. This is my first lager and brewday went great. I'm fermenting in a Sanke Keg using one of Derrin's nifty converters with racking cane, blow off and thermowell. I chilled to 65 degrees with my immersion chiller, then racked into the keg leaving most of the cold break material behind. I then placed the keg in a rubbermaid bin, filling the bottom 6 inches up with water and ice and managed to get it chilled down to around 50 degrees. I then oxygenated with O2 and carb stone and pitched rehydrated S-23 yeast. This morning when I woke up it was at 46 degrees. Before I went to work I setup my controller and fermwrap to kick on when it goes below 46 and added more ice to keep it cool. I plan to ramp that up to 50 and let it ferment at 50 until complete. It's sitting on my back deck, in the shade, but unfortunately the air temperature got up into the 60s today. Over the next weeks daytime highs are to be between 55 and 65 and the nightime lows between 45 and 29. I have no other way to ferment lagers and also don't have any means to record temperature fluctuations while I'm at work. Any thoughts on this setup or advice on ways I can improve the possibility of maintaining constant temperature?

well instead of relying on nature to control your lows and highs get a mini fridge. hopefully you have a two stage controller. if you do you can run both your fermwrap and the mini-fridge. this will offer a lot more control over the temp and protect your brew from the light.

Yeah, I know. Plans for a full size lagering fridge, glycol system, etc are in the works. Until then I'm trying to make do. Light isn't a problem since I'm fermenting in a 15.5 gallon Sanke.

I would recommend using some sort of insulated container if possible, and as big a thermal mass as you can get. Since you're using a Sanke keg, maybe use a full size garbage can with as much water as you can fit in it. Then wrap that with insulation or blankets.
Good luck

gxm, the thermal mass is a good idea. I've got it in a huge rubbermaid container, probably 4' long by 2' wide by 2' tall and have it filled with water to about half way up the keg. I add ice to the water as needed. The top half of the keg has the fermwrap taped to it and is covered by a doubled towel to make sure the heat goes into the keg and not dissipate into the air. So far from what I've seen, I'm able to keep it between 48 and 52. Hopefully those temperature swings don't result in poor fermentation.

As I left for work this morning there were still no signs of blowoff activitiy. As it's in a keg, I can't see what's happening with the wort. It had been about 30 hours since pitching at that point. Is this lag normal for lagers? Also, what should I expect to see with the ferementation (off gassing, vigorous blow off, temperature increase)?

keelanfish said:

As I left for work this morning there were still no signs of blowoff activitiy. As it's in a keg, I can't see what's happening with the wort. It had been about 30 hours since pitching at that point. Is this lag normal for lagers? Also, what should I expect to see with the ferementation (off gassing, vigorous blow off, temperature increase)?

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I'm not surprised by a long lag time, 13 gallons of lager is alot for a single packet of dried yeast.

I pitched two 11.5 gram packets of rehydrated dried yeast. I still think that is underpitched, but oh well. Still no off gassing from the blow off tube tonight, 48 hours after pitching. I gave it another 1 minute long blast of O2 and sealed everything back up. I also checked all the miscellaneous connections to make sure they were all airtight and that it wasn't offgassing somewhere else and it all checks out.

What should the top of fermentation look like with lagers? I shined a flashlight in it and it was pretty foamy.

keelanfish said:

I pitched two 11.5 gram packets of rehydrated dried yeast. I still think that is underpitched, but oh well. Still no off gassing from the blow off tube tonight, 48 hours after pitching. I gave it another 1 minute long blast of O2 and sealed everything back up. I also checked all the miscellaneous connections to make sure they were all airtight and that it wasn't offgassing somewhere else and it all checks out.

What should the top of fermentation look like with lagers? I shined a flashlight in it and it was pretty foamy.

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According to Mr Malty, 4 packets of dried yeast is what you'd need for a 1.052 lager, so you're definitely under-pitched. http://www.mrmalty.com/calc/calc.html
Anyway, foamy is good. Lagers won't give the thick krausen that ales have, but most of mine have 1/2" of foam which generally starts white and thin and becomes a dirty brown. It should still make beer
Be sure to check for diacetyl towards the end of fermentation, and maybe give it a d-rest at 60-65 towards the end of fermentation to be on the safe side.

Thanks for all the input gxm. I'll post updates on the progress.

Pleased to report that last night the blow off tube started bubbling about once every second. 72 hours of lag, but it's rocking now!

Update...Over the last few weeks I've gotten pretty good at maintaining constant temperatures using this setup and adding ice when needed. There is so much thermal mass that the trick is to look at the weather forecast and when the daytime highs are expected to be more than about 5 degrees above target temp, add ice during mid morning to get a head start on the cooling (wife has been helping with that while I'm at work).

As stated above, active fermentation started about 72 hours after pitching yeast. This long lag phase was probably the result of underpitching by about 50%. Ferementation was remarkably steady with the blow off tube bubbling more than once a second for seven days during which I managed to keep the temperatures between 49 and 53. On the eight day, I noticed the blow off slowed to about one bubble every 10 seconds. I decided since I underpitched to go ahead and do a diacetyl rest and warmed the fermenter up 2 degrees per day until I reached 58. By the end of this there was no airlock activity whatsoever and I decided to crash down to as close to 32 as I can get. It has been at between 34 and 37 degrees now for around a week.

Yesterday I pulled a sample (got to love the included racking cane in Derrin's Sanke converter). The sample was a little darker than I was shooting for, but not by much. Gravity was at 1.015, which is 3 points higher than I'm shooting for, but the OG was 2 points higher than I was shoothing for also. Targets were an OG of 1.050 and an FG of 1.012 (actual OG was 1.052). I'm pleased to say that the sample was remarkably clear, clean tasting and had no hint of butter or other off flavors at all. Still a little hoppy, but I think that will fade with lagering.

Next week I'm going to transfer to another keg and lager for around one month as cold as I can. Then I'll bottle, adding saved gyle for priming and will also add some priming yeast. Any recommendations on what yeast to add?