Is all grain more susceptible to primary overflow?

Hi all,

Looks like it’s been too long since I posted - had to sign up again…

I finally made the jump to all grain brewing! Made a lot of rookie mistakes on my first batch (maybe I’ll write another post about that for everyone to laugh at), but the airlock’s bubbling now, so I’ll call it a win so far.

This morning I woke up to find the airlock full of sticky foam. Having brewed with extract for 5 years, I’ve obviously seen a bubble-over before, but it’s only happened to me a handful of times in probably 50+ batches. This one shocked me quite a bit because (largely due to my rookie mistakes) I only had 4 gallons of wort in my 6.5 gallon ale pail. With all that extra head space, I never would’ve expected it to overflow.

Are overflows more common in all grain brewing? Or did I possibly screw something up that made it krausen more intensely than normal?

Height of krausen is usually a factor of a few things. Things that will cause more krausen:

  • specific yeast strains. Some are just more susceptible than others
  • gravity of wort. higher gravity ales tend to be more susceptible.
  • yeast pitch count. If you pitch more yeast than you should based on gravity, you risk blow off

Those are the big ones. There isn’t really much difference between all grain and extract as far as producing more krausen other than maybe your wort is more fermentable due to simpler sugars but I’m not sure if that could cause more yeast growth or not.

What’s your fermentation temperature?

To the list of things Matt mentioned that cause blow off, I’d add fermenting too warm.

You’ll get a lot more vigorous fermentation if you’re at or above the yeasts high temperature limits.

I think you nailed it dannyboy - I just checked the temp in the closet, and it’s 77°F! I put the fermenter in a different location this time, and now that I think about it the heating duct runs through the wall right behind this closet. Oops…

Looks like I’ll have to get around to my spring cleaning so I can make room in my normal fermentation locales. :slight_smile:

Thanks for the pointers, guys!

In general, you will get more krausen from AG. Extract has already been boiled, so the proteins that form krausen have been broken down.

I don’t know why I never considered that, but it shouldn’t have surprised me. That makes perfect sense.
When anyone talks about overflow in the primary, my first thought is always that they are fermenting too warm. I haven’t seen a problem with that since I got my temperatures under control almost a hundred batches ago.

The #1 reason for blow off is temps. OP, as you ferment, the yeast produce heat. If you ferment too warm, the yeast go into overdrive and produce more heat. That extra heat only makes them become more active thus continuing a nasty cycle.

For cheap easy ways to control the temps check out swamp coolers.

I did not know this… or at least I never knew that proteins were involved in krausen production.

I have found that wheat in the grain bill makes for extra blowoff potential. I safeguard by fermenting a few degrees below the recommended range.