Primary versus secondary - brew set up

[mmbrew]

I know there is a lot of info out there and I'm sold on the idea of leaving my AG brews in a primary for 3-4 weeks (except when planning to dry hop or adding fruit...).

My question is more related to my current brew set up and equipment(until I upgrade - that's another topic). I normally ferment (minimum one week) in a 6.5 G carboy with a blow-off hose (more head space - I often have spill overs into bucket with water) then rack to a secondary for minimum 2+ more weeks. The risk of a vigorous fermentation into the blow-off hose is the main reason I use a secondary. I usually use a US-05 or Nottingham dry yeast in a starter (100 Ml pre-boiled water chilled to 30-35C - no DME/sometimes priming sugar added to wake yeast up) with good results. I am probably over doing it with a primary and secondary and I'm all for saving time not to mention additional cleaning.

Question: If I use my 6 G carboys (less head space than the 6.5 G) and ferment for 3-4 weeks solely in the primary, can I remove the blow-off hose after 7 days (once the risk of blow over is finished) and quickly replace with an ordinary airlock hence no need to rack into secondary?

Should I back off on my Batch Size (currently 23L) to give me more potential headspace in the 6G carboys reducing the risk of overflows?

Thanks,
MM

[GAM]

I would use the 6.5g and transfer this gives lots of time to clean and sanatize. The 6g will spill more beer and the beer in either will have the head space filled with co2.

Sandy

[BasilD]

"The risk of a vigorous fermentation into the blow-off hose is the main reason I use a secondary." what are your concerns with having a mess go through the blow off tube Marc? I've always seen this as a closed system "aka" purged of all oxygen with little chance of infection, unless of course it becomes clogged ( which I've never had happen, even with an infected batch that blew so hard it went all over my wall).

[CartoonCod]

Question: If I use my 6 G carboys (less head space than the 6.5 G) and ferment for 3-4 weeks solely in the primary, can I remove the blow-off hose after 7 days (once the risk of blow over is finished) and quickly replace with an ordinary airlock hence no need to rack into secondary?

Yes you can remove the blow off hose after 7 days and replace with a regular air lock, thats what I do.

[LeafMan66_67]

[mmbrew]

"what are your concerns with having a mess go through the blow off tube Marc?"

I have had good results with the blow-off hose primary fermentation method, but recently I had a bad batch that I think (?) happened due improper cleaning of the blow off tube (3 1/2 years old)... I probably did not sanitize properly and potentially had some overflow go up the hose and back into the carboy with some un-cleaned gunk (I am guessing) which could have contaminated my brew producing an off taste. I have replaced the old hose with a new blow off hose and I am revisiting all my potential points of failure. It's a learning experience...