Blow Off or Airlock

I am doing my first fermentation, an apfelwein that I tweaked. I am using lalvin D47. Ok, At first I was using an Airlock when fermentation was just starting up ( 1 bubble per 30 seconds ) but then I noticed that there was kreusen forming ( I'm doing I gallon ) so I rigged a blowoff tube. Now the foam has retreated back down the neck of the jug. It is still there but for about 12 hours now it has stayed back where it is supposed to be. Can I replace my airlock or do I need to keep the blowoff rig.

And When I had the blowoff tube, I actually needed it because there was alot of foam going down the tube.

From my experience, once a fermentation has retreated back down a blowoff tube, it doesn't come back. If the temp had dropped significantly and you heat it back up, maybe then the fermentation would take off again and need the blowoff. But assuming its a normal fermentation, I would go ahead and use an air lock now.

It sounds like you are using a 5 gal carboy right? I have found that at the beginning use the blow off tube into a gal milk jug filled about 1/4 to half full of water, so it acts just like an airlock, when the foaming stops in usally about 2 days put an airlock on and you will be fine, as for what you are doind now just if the foaming has stopped put the airlock and keep an eye on it, it helps to time the bubbling to keep better track of it day by day

Airlock is back on. This is day 2, 3-4 second bubble.

New question, there are small carbonation-type bubbles in my airlock. It doesn't seem like it is effecting anything but I just wanted to know if that happens t you guys. I only put water in the airlock.