Originally Posted by Zbay
Is it normal to lose airlock activity after you open your primary cover? Maybe I'm just being paranoid but I would hate to have stunned the yeast and and possibly ruining my batch of mead.
Of course it is. If you reduce or remove the pressure that is allowing the airlock to bubble, then it stops.
If the ferment is slowing down and producing less CO2, then it can take a while before you see bubble evidence of activity. If you didn't manage to make a complete seal on the fermenter when replacing the lid/bung/cover then you'd have continued activity but no visible proof.
Which is why it's best to use gravity readings to monitor the progress of a ferment and not try and mistakenly use bubble activity.
You can't stun the yeast by exposing it to any air/O2 and while it depends on the ingredients and type of brew, it's not as easy as that to mess a batch up enough to have ruined it.