The pump requires you to prime a minimum of 10 units each time, so what you can do is prime most of your air bubbles out before you attach the tubing. (The thinking here is that a 3 inch piece of tubing is a lot less space for air bubbles to escape through, than through 20 inches or more.) Once you have hit the 10u mark - or if you are feeling especially dexterous, you can just do this part once you