Alright this is my first batch of beer and I am not sure what to expect. My brew is in the carboy and I have switched over to my airlock from the blow-off hose three days ago. When I first put the airlock on it was bubbling good. Now the last two days I have not personally seen a bubble make it through. I can see that there is pressure in the airlock because of the water levels. Is this normal or should i be concerned?