What happens if you don't clean the electrodes during a 320ppm run? Kephra already says that he filters the resultant product. What am I missing? Assuming you'll be filtering regardless, why should we clean the anode? Does the black flaky stuff interfere with the final PPM amount? I think I read somewhere on this forum that it doesn't (the junk on your cathode does however, but that shouldn't be a problem using sodium carbonate.)
I don't mind spending a couple bucks at the dollar store for a brand-new 36V power supply (4-9v's only $2.) Can I still use this setup to run relatively high mA's of say (40-80 mA's, assuming I have a huge anode) even if I only get a few runs because of the drain problem Kephra alludes to? And if I'm using rechargeable 9V's is this even less important of a concern? How much current could I run using the 7805 if I wasn't too concerned with battery capacity? If my cheapo batteries had a 450mA capacity, shouldn't I expect 10 hours @ 45 mA's (.75 liters at 15mA's=240 minutes for 320ppm | At 45mA's that's 1/3 the time ... so 750ml in 80 minutes (@45mA's.) So, approx. (7 x 750ml batches) for a set of batteries that cost $2. That seems reasonable, but if I were going to do a lot of batches, I'd see where you'd either want rechargeable batteries, or a plugin solution.
@Kephra, have you ever considered building simple "ready to go" current limiting circuits that just do that simple function without the "full-solution" complexity that obviously goes into your production units? If you could, for instance, offer folks simple, yet elegant, current limiter circuits "no frills style."
I bet people would line-up to buy your simple 2-transistor current limiting design at various pre-determined or variable mA outputs. A "no-frills" offering. If such a simple yet indispensable component could come to market for around $20 bucks, I bet you'd sell the hell out them.
Even though you obviously sell a very quality fully contained system, some folks, as you know, are more "do it yourself types" but wouldn't hesitate buying certain critical components. For instance, how many folks here read these posts and decide they need a magnetic stirrer/heater or current limiting diodes and then simply go out and buy one on ebay or whatever (because they consider it absolutely necessary.)
I suspect many of these same folks, lacking any electronics background, would easily prefer to just buy the darn current regulator circuit (IF ONLY SOMEONE SOLD THEM, and they were reasonably priced.)