Carboy size 3 or 5 gallon? please

Question

I've got a 15 litre, 3.9 gallon batch of hard cider (I juiced the apples myself and lost the will to live after 20kg). Should I get a 3 gallon or 5 gallon carboy?

I read that when moving the cider to a carboy for secondary fermentation I shouldn't leave a pocket of air. Will using a 5 gallon carboy and topping up with a litre of water greatly dilute my cider? Is it best to go for a 3 gallon?

Thanks for you help in advance.

Paul

Answer 1

1) Go with a 5 gallon primary, this is the one you want ample head space in, secondary filling to the neck minimizes O2 exposure. O2 exposure is only an issue once you have alcohol in the cider, there are several ways to minimize this in secondary.

2) I wouldn't dilute with water, it will only lower the OG reducing the final ABV

Answer 2

For the primary go with 5 gallons so you have plenty of headspace for any foaming.

For the secondary, i'l split between the 3 gallon carboy and get a 1 gallon jug for the remainder. This way you can keep the headspace to a minimum, and you have extra same batch cider in hand if you need to top off for any reason. Which you will because Apple drops a TON of sediment.