Not cleaning fermenter

[Nate]

We're doing back to back batches of the same beer only 2 weeks apart (Hefe) and I'm considering dumping yeast and then re-pitching the proper amount of yeast (with new wort) back into the dirty fermenter (Blichmann conical). The fermenter would never be opened and would be kept slightly C02 pressurized the entire time.

Asking for trouble? Just trying to avoid another fermenter breakdown, cleaning, reassembly and sanitizing...

 

[Stillraining]

Don't know if its possible but if you put your wort in at flame out temp and then had a way to chill it in the conical that would be a plus and definitely very safe that way. Probably would never have to clean it, and just keep the batches rollin one after another.. LOL

 

[pdxal]

There would be some hefeweizen yeast left in the conical but they would be outnumbered by your intended yeast. If you don't mind the possibility of a little hefe character in the second beer, give it a shot.

If doing the same beer- just like pitching on a yeast cake in a carboy, but with the ability to manage how much you pitch for the second batch.

 

[DurtyChemist]

You'll be fine. Even if the only way you had to cool was in a fridge/fermentation chamber you'd be fine because the hot wort in the stainless Fermentor would kill anything including old Hefeweizen yeast cells.

 

[Zepth]

Been there done that. Only when using the same yeast - for your repeat batch it will be no issue. I usually dump a good part of the yeast cake then toss cooled wort right onto it. Have yet to have an issue.

Probably not the best procedure to follow, but far from the worst.

 

[Nate]

Been there done that. Only when using the same yeast - for your repeat batch it will be no issue. I usually dump a good part of the yeast cake then toss cooled wort right onto it. Have yet to have an issue.

Probably not the best procedure to follow, but far from the worst.

Going to use this approach also but not sure how much yeast I'll pitch back... if any. The Weihenstephan throws a ton more banana (which we like) if under pitched so I may drain almost all of the yeast cake.

On second thought, for tracking and consistency purposes I guess I should drain completely, measure some out and then dump it back in...

 

[Nate]

Wanted to post a quick follow-up. Beer turned out great but the fermentation was interestingly different. We under pitched compared to previous brews and, as expected, it started about 6 hours later and was less aggressive but.... it finished 5 days quicker. Same grain bill, process, temperature, etc. Previous same beers have fermented violently for 24 hours and then go slowly for almost 2 weeks. This one started more slowly but finished stronger after only 8 days. Banana esters also seem less which contradicts what is expected from this yeast. Probably won't do this again but it was interesting to try.

Anyhow, just wanted to post an update for anyone else who plays with this yeast...

 

[DurtyChemist]

Interesting. How did you underpitch? New smack pack or just harvest from the previous fermentation? I'll be pitching on a yeast cake later today just because I want to test this recipe with a strong population of belgian yeast that are just finishing a beer right now.

 

[Nate]

Interesting. How did you underpitch? New smack pack or just harvest from the previous fermentation? I'll be pitching on a yeast cake later today just because I want to test this recipe with a strong population of belgian yeast that are just finishing a beer right now.

We dumped all of the cake from the conical and then pitched about a pint of slurry back into 10 gallons of fresh wort.

Good luck!

 

[Zepth]

If it was a pint of dense slurry I'd be thinking you overpitched. Brewers friend site seems to agree. Of course my numbers are both estimated and metric-ized so some variance, but 30% overpitch is far from notably under.

Wort Gravity (OG): (1.050)
Wort Volume: (40 Liters)
Target Pitch Rate: (ale regular gravity)
(million cells / ml / degree plato)
Yeast Type:
Slurry Amount: (1/2 Liters)
Slurry Density: (1billion cells / ml(default))


Cells Available:
500 billion cells
Pitch Rate As-Is:
1.01M cells / mL / °P
Target Pitch Rate Cells:
372 billion cells
Difference:
128 billion cells

 

[Nate]

If it was a pint of dense slurry I'd be thinking you overpitched. Brewers friend site seems to agree. Of course my numbers are both estimated and metric-ized so some variance, but 30% overpitch is far from notably under.

Wort Gravity (OG): (1.050)
Wort Volume: (40 Liters)
Target Pitch Rate: (ale regular gravity)
(million cells / ml / degree plato)
Yeast Type:
Slurry Amount: (1/2 Liters)
Slurry Density: (1billion cells / ml(default))


Cells Available:
500 billion cells
Pitch Rate As-Is:
1.01M cells / mL / °P
Target Pitch Rate Cells:
372 billion cells
Difference:
128 billion cells

I wouldn't rule it out... this was pretty much a shot in the dark experiment. I was assuming under pitch because I'd collected a couple other slurries, crashed in the fridge and compared the settled yeast against what we normally see in our starters. I probably also should have mentioned that the wort OG was 1.079 so it was a pretty big beer. Over pitching though would explain the faster finish and less banana esters. Even though we drained the cake, there's also probably a pretty significant amount of yeast still in the fermenter. Actually, the more I look at it, I think you're right.

Either way, it was an experiment and we'll probably just do starters in clean fermenters from this point on. We like the end result and it's a more repeatable process.

 

[Nate]

One last update post. After drinking this beer a little more, there's definitely some krausen bittering/aftertaste going on with the finish of this beer. Makes sense (to me anyhow) that all the krausen from the previous batch would have some impact on the next batch. This is especially a problem if you have more volume (even slightly) than the previous batch because the krausen ring is now sitting in your new wort.

Long story short, it didn't make a bad beer but definitely had an impact...