Small batch fermentation rate??

[hoppyhowie]

I just tried making a small batch for experimentation (2.5 gallons). I put it into my normal 6.5 gal carboy after reading this shouldn't make too much of a difference. It seems to be progressing nicely, however it seems that there is much slower fermentation. Its been 3 days now and I've noticed that it has peaked at about 1 bubble in the airlock every 8 seconds which is MUCH slower than everything else I've done.
Could this be due to the reduced load that there is just less overall material or do you think its something else? Thanks for any input!

 

[OlatheSurferDude]

I have done something similar but don't remember a big change. They say airlock activity doesn't represent fermentation progress. Maybe related to additional head space? How active does it look when looking at the liquid itself?

 

[hoppyhowie]

I'm thinking its the head space. It looks pretty active, large krausen with actually very large bubbles that I'm not used to. Thanks for the reminder that airlock activity isn't same as fermentation... just so tempting to think it is!

 

[OlatheSurferDude]

Glad to be of some help. I like using my glass carboy for my small batches. Gives me access to see what's really going on that I normally don't see when I do a 5 gal batch.

 

[Revvy]

Airlock bubbling means nothing, it's not a fermentation gauge. How much it bubbles or not has nothing to do with how active or fast or slow a fermentation is going. All an airlock is is a vent, a valve to release EXCESS co2 to keep the lid from blowing off the fermenter and painting your ceiling with beer. The reason it seems to be bubbling LESS with a small volume of beer in a larger fermenter has nothing to do with the rate of fermentation...it should be obvious, it has to do with the fact that you have a larger HEADSPACE, and therefore the co2 isn't needing to vent OUT of the fermenter as much as if it were in a tighter space.

Remember airlock= valve, NOT Magic Fermentation Gauge, don't correlate what the yeast are doing with how it is bubbling....

 

[hoppyhowie]

yeah, i'll have to rely on the gravity readings. It would be nice to have a gauge of how well things are progressing while you're waiting patiently.

 

[tektonjp]

I think it might actually be a math problem. One half of a normal batch will produce, um, just a second, getting my socks off so I can count, erm, maybe one half of the co2 of a regular sized batch? Just a guess, though.

 

[tektonjp]

Oh, sorry. Was I supposed to post an OT question? I get easily confused.

 

[elvestinkle]

My half-batches also outgass less vigorously in my 6-gallon BB. I'm pretty sure it's a headspace/volume thing--more volume means overall less pressure. It's kinda nice, actually; I can pitch Notty and not even care how big the krausen gets

 

[heferly]

You're messing with them, right?

Nah, just think he's trolling and posting bad info as fact

 

[hoppyhowie]

Yeah I'm thinking its the head space... I'll post back once I get the FG reading.

 

[9Frogs]

I have noticed the same thing, too. I use a 5 gallon carboy for my 2.5 gallon experiments. Last one went fine (Biermunchers Centenial Blonde-should have made 10 gallons!), second one is doing the same thing. Followed the OG and FG and all was well.