2 gallons in 5 gallons? OK?

I want to brew a few small batches just to experiment but only have 5 gallon buckets for fermentation and was just wondering is there any harm in putting a 2 gallon batch into a 5 gallon fermentor?

Will the air in the fermentor cause the beer any harm or will the co2 coming from the brew force the air out and protect the beer?

Or is all of what I've said pure nonsense?

well, you might as well use the whole space... but if you're deadset on making small batches, you can use a 5 gallon fermenter. just don't let it sit too long after fermentation is complete and you should be fine.

At the moment I dont have the facilities to do full 5 gallon boils so I'm taking it as a chance to try some odd stuff. I suppose I could have a look at recipies for some interesting partial boils but I figure I'll try some unusual small batches to see how I get on.

You'll be fine. Just dont use a secondary. The CO2 will keep a big blanket over the beer.

something you might try is splitting the boil between 2 or even 3 pots if need be... a lot of people who cannot do a full boil have successfully used this method.

I use my buckets for small experimental batches all the time. No issues what so ever. Listen to that drunken donkey up there ^ and follow his advice.

The problem I have with doing the small batches in those containers is that, especially if I am dry hopping, etc. it seems like the amount of sediment I get in the bottom of the fermenter is quite large compared to the usable volume of beer I end up with, and it makes it harder to rack the beer off without stirring it up. I would recommend either using a smaller diameter container, or upping the volume a bit to help with that part.

FWIW I went to the bakery at my local grocery and asked if they had some food-grade buckets they were willing to part with, and scored a 4-gallon and 2.5 gallon bucket that I now use all the time for brewing small batches. So, you might be able to find something like that.