Newbie question- fermenting in two carboys

[yrud12b]

I just brewed my first extract kit this past weekend. I have one 6.5 gal glass carboy and four 5 gal carboys. While my 6.5 is in use for two weeks, I thought about brewing another extract kit. Should I split it into two 2.5 batches and use two 5 gal carboys or keep them in one? I anticipate a loss of wort if I put the full 5 gal in a 5 gal carboy instead of 6.5. Is there too much headroom in the carboy to just have 2.5 gal of wort in a 5 gal glass carboy?

Thanks!

 

[Ozarks Mountain Brewery]

depends on how much foam expansion you get really, you need at least 3 inches of room on top for the yeast to create the foam layer or you'll need a blow off tube, I don't think it would hurt to split the batch into 2 but I my self like to ferment the whole batch in one vessel if possible just for the best possible fermentation.

 

[Nosybear]

How about simply brewing a four-gallon batch?

 

[yrud12b]

It's a 5 gallon kit. I guess I could calculate out the recipe and toss the leftover DME and LME, but I might as well just do the full recipe and let the blow off loss go. That would be less than losing a gallon, right?

 

[Ozarks Mountain Brewery]

one thing to note, the head space in a carboy means nothing as long as its sealed with an airlock or tube under water and never opened, the head space will push all the air out while fermenting and will not let any back in when done unless you open it, so doing the split batch will work just fine if you don't open it until its ready to rack

 

[Nosybear]

Good call on the 5-gallon kit, no need to throw away ingredients. Another option, less water - give yourself some more head space by brewing the five gallon kit using a fermenter target of 4 gallons, then once fermentation has settled down, add boiled, cooled water to bring it back up to 5.