Splitting 5 gal batch into two 2 1/2 gal batches

I want to make a couple of 5 gallon extract batches, and split then into two different primary fermenters to trial a few different ideas such as hop scheduel, hop variety, fermentation time and temp, yeast strain and so on. I do not have smaller 3 or 4 gallon fermenters for the 2 1/2 gallon batches that I will be working with, but assume that as long as I am only using them for a primary I should be able to use a 5 or 6 gallon carboy for my 2 1/2 gallon batches. The extra headspace wont be an issue due to the CO2 being produced. Is this a correct assumption?
Also, if I steep my specialty grains and then split the steeped water in half for the two 2 1/2 gallon batches, will the flavor/charactor of the steeped water change if I refrigerate 1/2 of it to use in the second batch a day later?

No problem using a 5 for primary with a half batch. i do it all the time. i also have 3s, but I use them for my secondary…do you have a plan for secondary or are you going straight to bottle?

there should be no issue with fridging the second half. just make sure it’s covered, or better yet, put it in jars/jugs with lids so it doesn’t absorb “flavors” from the fridge.


Or you could grab a couple of these:

http://www.lowes.com/pd_356492-1152-516 ... facetInfo=

I’ve got a 5 gallon batch that I split in two for the same reason (different hops) and these seemed to work fine.