Fermentaion question

[Midnightblue69]

I am making a batch of blackberry wine for the first time so please excuse my dumb question. I have just added my yeast to my must in my primary(first) fermentaion tub. I am using a 5 gallon plastic water jug for my secondary. I am yeielding about 3 gallons of wine. Do I need to fill my secondary fermentaion vessle(5 gal jug) to near the top before attaching my airlock? Or in other words Is 3gallons of wine in a 5 gallon jug allowing too much air to be present for proper fermantaion?

Thank y'all in advance!!!

 

[Yooper]

Once fermentation slows, you need to have it "fit" the fermenter. So, for a 3 gallon batch, you'll need a 3 gallon carboy or three 1 gallon jugs.

 

[Brewme1]

If you want a weaker/lighter 5gallon batch then add the water. Most people like a stronger/thicker style of that wine and would stick w/3gallons - if you want to only make 3gal then it might be a good idea to get a 3 gallon carbouy. The excess air won't hinder fermentation, but it may risk oxygenation which can ruin the wine. Yooper is right - either get a 3gal jug, 3 1gal containers or make it a 5gal batch, but if you do that it might be weak and watery.