Quote Originally Posted by amoose136 View Post
Capacitance would depend on the dielectric constant which also depends on saltwater concentration so I don't think we've saved much by measuring capacitance instead of resistance.

Laser interferometer with a floating mirror is better but as soon as you add another laser and electronics that can measure time delays that small you significantly increase monetary costs.
The saltwater is the conductor, not the dielectric. The dielectric is the container wall. It will vary from build to build, but remain constant on a single container.