if you are doing brf with the dry verm layer on top you don't need to leave the tape covering the holes. This will only slow down incuabtion time and could cause them to stall. The dry verm barrier will keep contams out just fine. You probably did a good thing by removing the air stone, I tried using bubblers in mine when I first started for air exchange but it dried out my fc and killed my humidity levels. What I do is I have an air pump in a small plastic tub with a hepa filter on top and run a hose into each side of the fc and pump fresh air in for 15 mins every 4 hrs. I also have holes in the side of my fc that are covered with tyvek so this provides total air exchange I never have to manually fan my fc.