G'day Mate,
The cause of "Ballooning" is quite simple, the aircraft has too much airspeed, when up elevator is applied to flair for landing, If this happens it is usually because of a not so great approach. A dive toward the ground, causes a buildup of airspeed, followed by a ballooning as up elevator is applied, easy to fix, just apply enough elevator to level the plane, at low throttle of course, at about 2 to 3 ft. off the ground, but not enough to raise the nose above the horizontal, the plane will loose airspeed & when you see the plane begin to sink again, this is when a gradual application of up elevator should be applied to flair for landing. It may take a few tries to get it right, but it will be worth the effort, & will save lots of broken props & bent landing gear.