Help w/ Fermentation Issues

Temperature? My guess with the info given is that you have too low a temperature and your yeast is floccing too fast. You are not rousing vigorously enough and when you rack you sufficiently mix the yeast and fermenting beer and it starts fermenting again.

 

How are to oxygenating your wort?

 

Definitely sounds like some sort of flocculation issue since it starts back up when you transfer to secondary.

If it sits at about 70 does that mean it drops below at all? It is possible that if it drops to the mid to high 60s after the initial fermentation has died down and the heat from that process has largely dissipated that that would encourage more rapid floccing than you want.

Another thought. How are you making your transfers? Are you oxygenating your wort when you move it to the secondary?

 

You could have higher CO2 levels because your beer is fermenting at a lower temp but I can't imagine it is enough to cause problems. As an aside, use a carbonation calc like this that takes temp into account. At a lower temp beer retains more CO2 in solution so adding a cup of DME to a beer that finished at 68 degrees will give you more carbonation than adding a cup of DME to a beer that finished at 75 degrees.

 

I don't have a suggestion, other that to ask yourself is there anything that you changed in your process starting with your last three batches?

 

I should have/meant to ask before... In addition to 'How are you oxygenating your wort (prior to fermentation),' are you making appropriately sized yeast starters (if using liquid yeast)?

 

Just to confirm, the aeration and pitching strategies you are using are the same as you used for prior batches in which you did not experience fermentation issues?

Cheers!

 

Have you thought about using a pure O2 source (like Home Depot disposable tanks) and a 0.5 micron stone? Shaking/swirling will get you so far, but especially for higher gravity worts, forced O2 is a great way to go. But if not pure O2, at least 'shaking' rather than 'swirling' the carboy will help. (Agitation is good.)

My guess is you will love the stirplate. Smaller starters (compared to 'simple' or 'shaken'), and faster turnaround. I found appropriately sized starters (for which a stirplate makes life easier) to be almost as dramatic as fermentation temp control in regards to improvements in my beers.

 

Thanks for that feedback. I confess that I am somewhat at a loss why you are now experiencing fermentation issues now since you didn’t experience them before using the same strategies.

There is no doubt that the suggestions you received from Vikeman are ‘good things’.

“Using a pure O2 source (like Home Depot disposable tanks) and a 0.5 micron stone” will certainly get you more oxygen into your fermenter.

Making a starter will certainly provide more yeast cells for your fermentation.

The fact that you didn’t experience fermentation issues before by simply swirling the carboy and pitching non-starters for lower gravity (less than 1.060) beers doesn’t 100% assure me that this is your problem.

Don’t get me wrong, I am not discouraging the use of pure O2 and starters. The fact that you didn’t experience issues before while not using pure O2 and starters leads me to believe that this is the root problem here.

For what it is worth I have brewed close to 300 batches. I have never utilized pure O2 and I frequently do not make starters for lower gravity (less than 1.060) beers and my beers ferment out just fine. I have never experienced a ‘stalled’ ferment and my beers complete fermentation (i.e., reach a low final gravity in a timely manner) just fine.

It certainly would not be a bad idea for you to try the pure O2 and starter process for your beers.

Cheers!

 

I think if you were building up too much pressure, the bell in your 3-piece airlock would be pegging the cover like a jackhammer. And once the airlock is quiet, it's because there is no significant CO2 pressure (vs. atmospheric pressure).

 

“ …it might be an issue of retaining too much CO2 and building up too much pressure.” I have no knowledge of “too much CO2” being a problem/issue. It seems to me that as ‘excess’ CO2 is produced it will simply bubble out of the fermenter.

“Maybe I'm not leaving enough headspace in primary,” This is another topic I have no familiarity with. I know that some homebrewers brew in 6.5 gallon carboys and I have yet to hear them express fermentation issues in this regard.

“maybe I should ditch the three-piece air locks for some wider blow-off tubes.” You certainly should use a blow off tube if you are experiencing ‘excess’ krausen. Otherwise, a three-piece airlock should be OK.

I apologize for not having any good suggestions to help you with.

Hopefully somebody else who has not chimed into this thread will have some good ideas.

Cheers!

 

Have you calibrated your thermometer lately? A very high mash temperature could cause the problem you're describing (lots of unfermentable dextrins). I once had the opposite problem; my thermometer was reading 6F too high and I brewed 2 batches before catching it. 82% attenuation for a Scotch ale kinda sucks