It just occurred to me that if a person started out with say a gallon less wort in the primary and then added that gallon after the first few days of fermentation, you may not need a blow out tube. I know if I just had a 6 gallon primary that would take care of most of it but I already have two really nice 5 gallon glass carboys. This seems like a simple fix. Anybody have any reasons why this wouldn't work? I am thinking of making round 2 of BBHB (Big Black Hop Bomb) mostly because it's a crappy day out and trying the just add water latter idea to see what happens.
The one downside i can think of is that you won't be able to get a reliable starting gravity, but this is a non issue if you are doing a kit, as they already give it to you. I suppose you could probably calculate it somehow.
That was the only down side I could see, but I really don't care what the SG is. To me it's just a number and it is what it is what it is and once it's said and done... I can't change it, other than add more water and here we go again with the 5 gallon carboy. Round 2 is on the wood stove right now and should be starting her boil in a few minutes. Yeeha!