Technical, DE5000 vs Ohmmeter DC measurement.

[Qmavam]

A little background, Making an electrostatic treatment vessel with an emulsion to be treated. First tests were with a test tube and a wire inserted in the center as one electrode. The test tube was inserted in a metal tube as the other electrode. Test have shown the emulsion has enough conductivity that the electrodes must me insulated from the emulsion. To that end we made to aluminum plate 2" x 5" and dipped them in fiberglass resin epoxy, twice just to make sure. The plates have a nylon spacer holding them 1" apart. After it was all cured we set the plates in 4" of tap water connected a DE-5000 and set it for DCR the reading was 1.4MΩ. I expected much higher or higher than the meter measures, or maybe not because it will measure 200MΩ. This being confusing, I got my Bryman BM235 and measured the plates in the same 4" of water. It read an open as OL on the screen, which is what I would expect. I connected my DE-5000 to the scope and it does output DC when measuring DCR (I had to verify). So why the difference between the two measurements?
Additional info; in air the plates measure 4pf, in 4" of water, that jumps to 2.2nF.