Heavy Housing

[fppf]

I just use plan PVC.

I went a little more complex, on the end screw in cap I drilled and tapped an 1/8" NPT port. Then screwed in a small ball valve. The PVC empty will make the rig positive. Then I just open the valve a little at a time until the rig becomes neutral. This provides a way to adjust the buoyancy. Once its set the PVC does not crush so it never changes. Works great in fresh and salt water.

 

[Video rookie]

Just an update:

I assume that the compression of the air in the tubes at depth made it less effective. QUOTE]

Provided the shape of the float remains constant, I believe the amount of bouyancy will also remain constant. I'm sure someone else will correct me on this if I'm mistaken on this....

 

[fppf]

Correct, if the container is ridged and does not compress its buoyancy wont change.
The gas in the tube remains at 1 atm.

 

[ScubaDocER]

Thanks guys. The tube is rigid and does not compress. I may have just needed more tubes.