Having no airlock activity despite krausen being present is nothing to worry about, as this can still mean you have healthy yeast. In fact, most brewers use an open-lid method since the krausen is thick enough to limit the entry of oxygen. Nevertheless, there are many causes for having plenty of krausen present in your fermenter but with little to no airlock activities. One of these reasons is that maybe there is a leak in your glass carboys or plastic airlock. To remedy the leak, you can follow these steps: Push the airlock or the lid down, Tighten its closure, Replace the plastic or carboy airlock.