As you will read later, for a successful ferment vegetables need to be tightly packed underneath water without any air bubbles. This is either under their own naturally produced water or under an added brine. Failure to ensure this liquid coverage is one of the main reasons for an unsuccessful ferment. I meet many people who say their ferments have started to mould or tasted ‘off’ when trying it. This may well be because the vegetables were not completely submerged in water. Check your ferments are underneath water regularly, adding more liquid if needed. And to help the ferment stay underwater you usually need some sort of weight to push it down.