Significant gas generation has become a problem in cell no.10, due to excessive water in the substrate the environment is favoring some kind of fermentative species. This is causing the surface of the substrate to change elevation and the gas(likely co2) is displacing the o2 that needs to reach the cathode.  

That lovely burst of energy yesterday was quickly suffocated over night, as the substrate rose at least a quarter of an inch.

I gave the cell a good two or three hard taps on the table to get some of the bubbles out, the voltage had dropped to somewhere around 222mv, it's back in the 240s now but I'm considering removing some of the insulation so the fermentation slows or stalls.  This cell isn't designed for a fermentation so it's causing all kinds of trouble.