Odd cloudy beer problem

[KaskaskiaBrew]

I've had a few batches that don't seem to be clearing up and some even give a yeasty flavor (even after a few weeks of cold conditioning) so I performed a test recently. I brewed a full 3bbl batch and a 5 gallon batch of the same exact recipe with the same water and the same harvested yeast at the same time. Within 3 weeks, the 5 gallon batch dropped clear (fermented at room temp around 74) and the 3bbl batch (fermented at 68) still had a slight yeasty flavor and was still a bit cloudy. The larger batch hasn't been cold crashed yet to really get the yeast to drop but I'm stumped why these beers don't taste the same after the same amount of time. My only guess would be that the larger beer hasn't been oxygenated enough or I'm either overpitching/underpithing the amount of yeast. Normally I add about 1pint/barrrel of thick slurry and I used that same slurry to ferment the smaller batch. I didn't oxygenate the smaller batch and it still fermented faster and cleaner than the oxygenated bigger batch. Our water temp is still a bit higher right now so I can also only get the bigger batch down to about 85-90F and then it cools the rest of the way in the fermenter so could this be the problem? My next step is going to be to take a 3bbl batch and pull off 2 carboys and ferment them on their own to see if they have the same yeasty problem. Overall though, I'm overly stumped on this one.

Cheers,

[TL Services]

My first thought would be to check yeast viability. It may be that if you're just cropping and reusing that you're getting a high proportion of dead and/or weak cells.

Another possibility, which you mention yourself, may be oxygenation control.

[brewmaster 2011]

I would say that it might be the fermenter hight? a 3 bbl fermneter is alot taller then a 5 gallon bucket so the 5 gallong will come out clearer then the 3bbl.

[KaskaskiaBrew]

Thanks for the responses guys. I'll double check the oxygenation and the yeast health before pitching. I'll do a few more tests and see if I can narrow down the problem. My guess is that I am underpitching the larger batch and I used the right amount on the smaller batch.

Cheers,

[Bierkoenig]

What Brewmaster 2011 describes is almost certainly what you're experiencing. Try this experiment: take about a half liter sample in a jar from one of your fermenters when you crash the tank and put it in your cooler. When the beer in the jar drops bright, pull another sample off the tank and compare. There will be a significant difference. This is why titrating finings in jars doesn't give an accurate measure of how much fining you need in the tank. In the jar a particle need only fall a few inches, but in the tank it has to fall several (or more) feet--that takes a lot longer.