doubling fermintation size

[Imakewort]

not sure about this procedure, I want to double the amount of wort i can ferment. Say I have a 15 gallon system and want to use a 30+ gallon conical, Do i start 15 gallons then 12 or so hours later brew again and add another 15 gallons after fermentation starts? Also what is the rule for selecting the proper conical, if you want say total 30 gallons use a 4o gallon conical to account for krausen and blow off and dry hopping?

[BDawg]

Yes, that's exactly how many brew pubs do it.

[ajdelange]

Filling a fermeter with multiple brews is done at all levels of scale.

25 - 33% head room is good.

[captain carrot]

Fermcap is suppose to reduce blowoff when used during fermentation allowing maximum utilization of fermenter space. I couldn't find any figures but here's a link with more info.
http://www.brewing-solutions.com/produc ... ails&id=10
I use it when boiling yeast starter on the stove. 2-3 drops works great in stopping boil overs. It's not supposed to effect head retention in the finished beer. I bought mine from Williams.

[BayouBrew]

You may want to email Matt Brynildson from Firestone Walker about it. On the 8-21-05 show (about the 3hr 17min mark) he briefly mentioned doing exactly what you are talking about. He didn't give any details, but he would probably be willing to answer any questions you have.