Regardless of the method by which the energy is being coupled into the tank (and we can debate this further) the voltages are quite real, and quite high for a sufficiently isolated tank. The currents, however, are so small that they very nearly defy measurement with laboratory grade equipment. In all cases tested for this paper, no voltage was detectable in the tank when the titanium ground probe was properly connected to (earth).
So if you now accept this as the normal case for SW tanks, you begin asking yourself if this is a problem. I have discussed this with several educated folks, and we have concluded that the minute currents in the tank, due to grounding with titanium probes, are much less significant than unterminated voltages on the order of tens or hundreds of volts. We could not conceive of a case in nature where the volume of water would consistently be charged to 80 volts, but could very easily see situations where nano-amp currents would flow throughout the media. It was the consensus, then, that it would be better to ground the tank, in that it would more accurately simulate the electric environment found in nature.
This is not to say that when equipment fails (insulation on power cords, for example) that fatal currents cannot be impressed in SW tanks.