I think I messed up a bit...
Last cider came out very nice, so now friends want to copy.
I decide to build up a little starter, using the remaining yeast from a drinkable bottle. Just added apple juice and it sets of proper.
My mates decide to take the straight bottle yeast, so I got this starter going, but with enough juice (in my opinion).
Normally fermentation is about done in 5-6 days and time to bottle.
So, 6 days in, i decide to top up the bottle with apple juice and close the lid.
Yesterday, I check and it looks like the level in the bottle has gone down...
I look again, and the bottle has a very different shape from usual. Much wider....
I've put the bottle in a coolbox, and am awaiting explosion