I've seen PaulB's method before, but it's a bit scary using electrodes in the tank, plus that method releases chlorine gas (and maybe even metallic sodium) - both are poisonous and lethal stuff. With the amount of Majanos I've killed off I probably would have gassed myself and/or killed my tank. I used to wonder if it was the current that killed them, the chlorine gas, or a combination of the two.