Sandie, in your class, you've learned about pressure changes and their effects on air spaces, like your middle ear. You know that going from the surface to 33 feet will compress an air space to half its original volume. On the other hand, going from 33 to 66 feet just reduces the volume by a third. What this illustrates is that the PROPORTIONAL pressure changes are greatest in shallower water -- and the shallowest water anywhere is in the pool. When you are practicing buoyancy exercises in confined water, you are rarely terribly stable and often quite unaware of the depth changes you are undergoing. Even sinking a couple of feet can really tweak your ears, especially at the end of a class, when you have been doing multiple ascents and descents and your ears may not be clearing as easily as they were at the beginning.
When you try to Buddha hover, and fall over on your back, your head is undergoing a descent, even if your center of gravity isn't. Therefore, the pressure in your ears is changing, and you need to equalize. If you are anything like I was in my class, as you are falling over, you are thinking about just about anything and everything other than your ears, and it isn't until you have regained some kind of stability that you realize your ears hurt.
When you try to Buddha hover, and fall over on your back, your head is undergoing a descent, even if your center of gravity isn't. Therefore, the pressure in your ears is changing, and you need to equalize. If you are anything like I was in my class, as you are falling over, you are thinking about just about anything and everything other than your ears, and it isn't until you have regained some kind of stability that you realize your ears hurt.