I am looking at building a machine that roams underwater, most always completely submerged. I would like at one point for the device to return to the surface and was wondering if it is possible to use electrolysis to turn the water into gas enough to provide buoyancy that would lift the machine out of the water? I have ran a few buoyancy equations and the machine will weigh in just under 10lbs. I would like to know if this is even possible, and if anyone can tell me the amount of O and H are needed to raise the 10lbs object. Thank you for your time!