where the valve is. if you have a helper ask them lift the valve up several inches away from the water so that the water will not spill over or spit out of the valve as you herd the air bubbles towards the valve. you can also use a broom handle or something similar such as a yardstick, to herd the bubbles to the valve. just make sure there are no sharp points on what ever you use. if you have a tube bed lift up the end of each tube one at a time, take the cap off the tube and run your hand the length of the tube 