Underwater Camera Buoyancy - how to check and correct the buoyancy of your underwater camera setup

I recently upgraded my underwater camera from a cropped sensor to a full frame DSLR. As the full frame setup is much heavier, I wanted to make sure that the buoyancy was correct for comfortable diving. I'd like to share how I went about calculating this and what my findings were in the hope that it will help you check and correct the buoyancy of your own underwater setup.
Did you try this? Did it work?
Let me know if you have any comments or questions!
www.katejonker.com