I built a Hoffman apparatus with graphite electrodes. I hooked it up to a make shift power supply from an xbox powerblock. It was filled with battery acid for the electrolyte. Now, the graphite electrode is 99% graphite rod. For some reason the graphite electrode on the negative(black) connection turns to powder. It stops producing gas; upon inspection, I find black mush floating in the electrolyte. Can anyone shed some light on the reason why? I'm tired of redoing this. It also happened with corrugated graphite ribbon electrodes.