For some of my upcoming brews I am thinking of scaling down to either 2.5 or 3 gallon batches and seeing what I like and move them up to 5 gallons later on. My question is, I have a 6.5 gallon fermenting bucket and 5 gallon keg. Do I need to get a smaller bucket and keg to do smaller batches? My ultimate goal is to take the smaller batches and turn them into 5 gallon brews once I know I like them. Or is it really not worth it and just stick with 5 gallons and keep on experimenting?
Nope, you’ll be fine with those.
When I decided to go No Sparge, this caused me to readdress batch size due to the volume of my MLT. I had to move to 4.5 gal into the fermenter with 4 gal into the keg because of the ~7-7.5 gal for the average full volume mash in the MLT. So far so good.
This also caused me to look at my fermenter.
I have a thermowell in the fermenter lid that reaches down into the wort. I was concerned that reducing volume into the fermenter would leave my thermowell high and dry. Fortunately it didn’t cause an issue and I realized it will reach down to the 3-3.5 gal level or so.
I say all that to say this: when you move from one batch size to another it can affect accoutrements attached to the various vessels in your arsenal. Just think thru your processes to ensure you’re not making a major impact due to a small change.
Disclaimer: Any comment I add is simply the way I brew beer. I am not paid or sponsored by anyone. There are certainly other ways that can be equally effective which other brewers may contribute. This is what I’ve found that works for me using my equipment and processes so I offer this for your consideration. YMMV
Generally no, I wouldn’t worry about it. I’ve fermented as small as one and two gallon batches in the typical 7.9 gallon buckets. I used to ferment three gallon batches in that bucket all the time. I’ve since moved primarily to fermenting that size in five gallon corny kegs, also without issue.