Just a couple quick questions

I have a couple of quick questions.

First, I understand airlock activity is not directly connected to active fermentation, and that you can have fermentation with little or no airlock activity. What I want yo know is this, if I have airlock activity, what else could cause it, aside from temperature fluctuations of course. For example, will an infected batch bubble away like a ferment will?

Second, will batch size effect fermentation time? For example, if i brew say 6 gallons of wort, and then placed 1 gallon into a 1 gallon jug, and the other 5 into my 6.5 gallon primary, and they are kept at the same temperature, will the 1 gallon batch finish sooner, or will they both finish about the same time?

I have a few batches under my belt, so I am no longer ultra paranoid about whether or not a batch is working, I just realized I didn't have any answers to these questions.

First, no airlock activity is usually not a good thing. If you have a good fermentation going you'll get activity. That said, just because it stopped doesn't mean that it is no longer fermenting. It is a good indication of activity but not a good indication of inactivity. I've never had an infected batch in 15 years of homebrewing so I don't really know what that would look like. That in itself says something. It isn't like I'm always the most careful brewer. What I have seen though is different types of yeast (Ale, Lager, Saison) will ferment differently and I'd think an infection would look different too.

Second, as far as I know it will take just as long for a small batch as for a large one. But that's if all things are equal, such as equal parts yeast to wort size. So if you mix it all together then split it into a 1 gal and 5 gal as you suggest, it should still take the same time.

As far as the airlock activity, I was just wondering if a bubbling airlock could mean anything other than fermentation. Having not had a batch go bad yet myself, I am just curious since I pretty much leave the fermenter alone for the better part of 2-3 weeks once I see bubbles, so I am always wondering If I am going to open the bucket one time to find it has not gone as planned even though the airlock told me it was fine.

Well, an airlock's not going to tell you *anything* about an infection one way or another. Batches with infections still ferment for the most part in exactly the same way.

Ahh, ok, interesting, I guess I was assuming if bacteria moved in, they could beat the yeast to the punch so to speak, causing the ferment to stall out early on. Though That would explain what little I know about sour beers...

Well, I suppose they could and I suppose they do sometimes. but they could also infect as the fermenting precedes anyway. Or they could kill the yeast and take over and continue to ferment by their own rules this time. Or just about anything. No way you can tell via air lock activity. ... My last two batches had lacto infections. Didn't effect fermentation at all.

I have read that infections can cause the fermentation to go further than normal. For example if the yeast used should take the FG to 1.010 an infection might take the FG to ? maybe 1.005 etc? That in itself might not be so bad but the flavors would also be compromised. You might see normal activity in the airlock but have strange looking krausen and bad smells and flavors.

As far a batch size, I could easily see that having an effect on time and level of fermentation. Not necessarily to any detriment.