First re-pitch: fast fermentation but low attenuation?

[CharlosCarlies]

We're a brand new production brewery and honestly this is the first time I've ever re-pitched yeast at any level simply because it was cheap enough as a homebrewer.

First beer was a 1.052 Pils using a freshly hydrated pitch of W-34/70. We've brewed it twice and hit ~74% AA both times w/ a 100% Pils malt bill and 154F mash temp. It's been taking about 7-10 days to hit terminal.

The beer in question is a Schwarzbier (first time brewing it) w/ about the same OG, but it looks to be almost done at ~67-68 AA after only 4-5 days! Grain bill was ~50/50 Pilsner/Munich w/ ~5% Midnight Wheat. We ended up mashing at 154F as well which I'm starting to think was a little high given the grain bill. Samples taste great, but is ~1.016 closeish to what yall would expect from a 1.048-1.052 Schwarzbier?

Other details:
- First beers were always fresh dry yeast w/ no O2
- Don't have a DO meter yet, but should have added plenty of O2 for the Schwarz.
- Pitched at ~49-50F
- Fermentation kicked off in a little over 12 hours which is significantly faster than we're used to w/ this yeast

Thanks for any help guys!

 

[Rivenin]

Funny thing is... i did almost the same thing with the same yeast (only oktoberfest > schwarz...). the oktoberfest went from 1.050 > 1.010 and the schwarz, unfortunately, my hydrometer met its demise... so i couldn't tell you for sure what happened. But i'd like to know about this as well (and first time repitching yeast as well haha )

 

[CharlosCarlies]

Can't count how many hydrometers I've broken, so now I always have at least two lying around!

What was your mash temp and grain bill like on the Oktoberfest?

 

[CharlosCarlies]

Looks like things are getting even weirder for this beer. I've taken gravity everyday this week and it was definitely at terminal around day 4-5 when compared to a fast ferment test. That rules out a yeast issue in my mind, so if anything we probably need to mash lower next time.

It's been about 7-8 days now and I just did a forced warm VDK test and there's almost no trace of diacetyl. On top of that, we missed the chance to ramp it up near the end of fermentation (since it was so fast), so we weren't even able to do a proper +5-10F diacetyl rest. It tastes great actually, and I'm even considering crashing it now since VDK was negative.

If nothing changes, we're looking at a very drinkable lager in 10-14 days if I really wanted/needed to crank it through. I dumped yeast this morning and there definitely seemed to be more than usual for this strain, so I'm wondering if a combination of over-pitching and over-aerating led to such a fast (and fortunately clean) fermentation. Considering this, I'm not going to re-pitch this culture again, but I certainly would like to figure out what the hell happened for next time!

Any other thoughts to add?