I usually pick up a sachet of yeast and a tub of nutrient from a well known high street shop that sounds like Bilko. Whether I am making a one gallon demi-john or 23lt bucket load I have always only chucked in one sachet, though I might varythe nutrient a bit. Today, I visited my local(ish) brewshop and picked up some yeast and nutrient. The bloke in the shop said there was enough to do 5 litres. Does this mean that I should really be using more yeast for larger vessels? I can see that it might take a little longer to get a fermentation going if you have less yeast, but surely it will multiply as long as there is sugar to consume?