I have just started my first 2 gallon demijohns of juice. I read that campden tablets should be used first to kill off bacteria but it has started to ferment before the campden tablets went it. Is it better to leave it fermenting and see if bacteria spoils it or should I add campden and re-start it with yeast? Thanks Ron

Just an update on what I have produced.

I made 6 demijohns of cider in Sept/Oct and in early December transferred all to 1 litre plastic bottles adding a teaspoon of caster sugar to re-ferment and give a bit of fizz to them. I tried one of them over Christmas. Nice fizz, light colour, clearly apple flavour but very dry. An old cider drinking friend of mine said it was just as it should be but its too dry for me (a bit like eating blackcurrants with no sugar).

This is probably very unorthodox and will be frowned up on by some but it works. I have opened and added 2 teaspoons of caster sugar + 3 of Xylitol, dissolved in some of the cider, per litre bottle and resealed it. I did this with 4 bottles and after 2/3 weeks, have a very nice cider, not unlike 'Magner's'. The sugar re-starts the ferment but Xylitol is neutral. Just for safety I put the re-started bottles in a big plastic bucket, with a towel over the top.

  • It does smell yeasty/fruity. It has thrown a sediment about 2cm thick and has cleared considerably. It has a fairly frothy surface. I think I will leave it alone and see what happens. Commented Sep 10, 2017 at 19:28
  • I would recommend NOT using Campden tablets with yeast ferments. Campden tablets are fine for removing chlorine from tap water or for stabilising the brew once it has finished fermenting. But IMHO Campden tablets and live yeast are not the best of play mates. Commented Sep 13, 2017 at 17:00
  • Thanks. It seems to be going along nicely with nothing added. Clearing well and a good amber colour. Commented Sep 14, 2017 at 21:59

1 Answer 1


Try to smell it. If it smells only yeasty or fruity, the yeast you pitched is strongest and everything is probably going fine. Leave it fermenting.

If it smells sour, something else has taken over. You can try to save the batch, but it may be too late.

Did you take a gravity reading? Take another one and see how much they differ. If not too much, you could try stopping and restarting fermentation, but it most of the sugars are already gone, new yeast won't do you much.


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