Could this work? Hydro Gravity Wheel

[mapsrg]

GREAT CONCEPT...HOW ABOUT PUTTING THE WHOLE THING UNDER WATER AND PUMP AIR INTO THE CYLINDERS/ BALLOONS  AT BOTTOM AND FLOODING THEM/ DEFLATING THEM  AT  THE TOP ON WAY DOWN.THE BELT COULD INCORPORATE A TRANSFER MECHANISM FOR THE AIR ,THE WHEELS AT TOP AND BOTTOM COULD CONTROL VALVE ACTIVATION.......OR PRESSURE VALVES COULD BE USED .......IT WOULD BE LIKE A STRING OF SUBMARINES BLOWING BALLAST ON ONE SIDE AND SINKING ON THE OTHER........IN THIS WAY YOU DONT HAVE A PROBLEM WITH A WATER SEAL MECHANISM.........

[Gearhead]

The reason that this device will not work is that flotation requires displacement.  When you force the float into the water it displaces water upward.  When the float is removed from the water the water returns to its original state ,assuming no leakage.  Displacing the water at the bottom cancels out the energy that could be obtained by the flotation of the float.

[shruggedatlas]

Gearhead,
If the flotat enters at an angle higher than 45 degrees to the axis it is rotating from, it will move upward. It would take a lot of floats as well as a tall reservoir. This would allow for two or 3 floats being in the water at the same time.
  The space between flotation devices can be sealed just like the floats themselves.
While it would be perpetual motion, it would be nothing more than a curiosity.

Sorry, but Gearhead is right.  You misunderstand the principle of flotation.  The reason something floats is because water below it is pushing it up.  No matter what the angle of the float coming entering the water, there is no water below it to push it up, so it still has to fight against the water pressure to get itself into the tank, and there is not enough energy for it to do that.

There is no way for this device to work, even if you had a perfect seal.

[mapsrg]

heres a sketch of a chain of tanks......

[shruggedatlas]

But I do believe an inverted water wheel can work because the float would enter the water or medium at a downward angle to its' axis. And since it would be partially in the water/medium, it would be lifted.

This is the part I have an issue with.  At the precise moment the float enters the water, there is no water under it to make it float.  It has to be pushed in.  It is not "lifted", as you say - that is an impossibility.  This is easy to illustrate with a real world example.  If you have a drinking straw of water that you are sealing at the top with your finger, you basically have a column of water with air under it.  Why does the column not "lift" the air under it and draw it up?  Because there is nothing to push the air up.  On the other hand, if there was an air bubble in the straw, it would rise, since there is water under it pushing it up.  I hope this is clear.

And do not worry about seals and friction.  With a perfect watertight and frictionless seal, you still cannot get the float into the water, much like air does not just get sucked into the drinking straw in my example.

Regarding your underwater device; I am confused.  Sure, it will work as long as the pressurized tanks supply air into the system.  But what happens when the tanks run out of air?