it becomes stranger 
i had the cell run at 1.5amp 9V IN (3.2V directly measured between the tubes) and measured the Ohms between inner and outer tube while running: >17MOhm
How can a current flow with a resistance 17 megaohms?? The voltage has to be incredibly high for even a little current to flow. 
edit: oh i got a resonant circuit with variable resistance now.. have to calculate it all .. dont mind
You can't measure resistance with a DVM while there is a voltage present, it gives a false reading.
The DVM sends a very small current and measures the voltage drop across what you're measuring, so if there is voltage from a source other than the DVM, the measurement is hosed.
The water will also hold a charge when you shut off your PWM or other voltage source. Therefore you must either discharge the voltage, wait for it to dissipate, or change the water before taking your measurement.
The same goes for taking capacitance measurements on your cell.
Are you pulsing the cell? If so your voltage measurements are not right either. The DVM set to DC volts can't measure a pulsed signal correctly.
Mikemongo