I had an idea (may have been done before):
What about dipping 2 opposite sides of a squared cell into some marine goop so it forms a thin "goop wall" on the sides of the cell. Then if placed into water with only the top and bottom-sides "open" (not sealed up), do you think that the water after heating would be forced by convection current to flow upward and around then down the sides of the cell, thus would maintain the a cooler temperature the unit, hopefully knocking bubbles upward off the plates, and the sealed edges also would prevent stray current from leaking out.
thoughts?