How to make a balloon float in the air? Adequate helium To ensure that a helium-filled aluminum foil balloon floats in the air, it should be filled with as much helium as possible. When filling helium, it is best to use a tube to inject helium directly into the inside of the aluminum foil balloon. 2. Increasing Buoyancy In addition to adding enough helium, it is also possible to fill the aluminum foil balloon with a certain amount of air before injecting the helium into the balloon.