Hi list, I did some experiments with DC polarity switching which are interesting. I use a constant current supply of 1.67 ma into #12 silver electrodes 3.9" of weatted length spaced 1.25 inches apart. "Brewing" time is two hours starting with 1.6 uS DW, no additives. I can start drawing 1.67 ma immediately as the generator can keep a constant current up to several hundred volts. Typical starting voltage is about 140, which drops over the two hours to around 12 volts or so as the conductivity increases.
The control batch (no polarity switching) ended up measuring 16.2 uS. Switching polarity every 17 seconds produced 7.8 uS. Likewise, switching polarity every minute produced 7.8 uS. The polarity switching does indeed keep electrode sludge buildup low, but at a cost of reducing the strength by about 48% for a given run time. Question - why the dramatic reduction in strength from polarity switching, when all other conditions are the same? It is interesting to monitor the voltage drop across the electrodes during polarity switching. At the moment of switching, the voltage drops for a second, then rises above the nominal state value for 8 - 10 seconds, then returns to nominal. Must be some interesting dynamic electrochemical "readjusting" going on when the polarity shifts. I did another batch with no polarity switching, but constant gentle stirring. It produced a 18.5 uS product (slightly "stronger"), but still had a bunch of sludge buildup. But I have to agree with Trem, I think stirring has some benefits, but they are not very overwhelming. I will see how the long term stability compares with the control batch. --Steve
