Great question if you don't have a vacuum sealer and want to use ziplock bags instead. For the water displacement method, you need to add the chicken breast to a sous vide safe (high temp) ziplock bag. Don't seal the bag just yet! Then push the bag under water, allowing the water pressure to push the air to the top of the bag, forcing it all out the top. Once all the air is out, you can seal the bag tightly and sous vide cook chicken breast without it floating to the top of the water bath.