I'm new to the forum and just started all grain brewing (previously did partial mash). I made a Holiday Ale and when I was done boiling I had 5 gallons of wort in my plastic bucket fermenter. When I transfer it into the secondary fermentor (carboy) there will be a lot of head space. I've been told that you don't want any head space because the air increases chances of spoilage. Is this true? If so, what is the best way to fix it. I was told by my father to add water to the top. I don't want to water down my beer so I would think this is the best thing to do. Any guidance is appreciated.