Yes, there is a tube that you put near the eggs and the other end goes into the container. An air hose is inserted near the bottom of that tube, in the side, near the eggs. The bubbles go up the tube bringing the water and fry with it.
It's like the old UG filters. It is just air bubbles going up a tube pushing water. I have a picture of it in my book but I don't have a picture of it I can post.
Oh! That makes sense! Thank you for clarifying! I like this idea a lot.