Re: current regulating diodes:

Thanks Estee!

The current rating is proportionate to your electrode size. More specifically your Anode(positive electrode). And the rule of thumb on this is typically 1mAh per/sq. inch of wetted electrode. - This has proven to be a good rule to follow in most cases.

I am using 12 awg silver wire with 3" immersed in the water.  How do I calculate the surface area?

As for the cathode, it's usually best to try and keep an inferior Cathode to Anode ratio(1:2 or better). Which is a very good way to establish and maintain a safe current draw on your Anode. Though there is no rule of thumb here as the parameters will change according to electrode size, temperature and initial solution volume.

You mean, if the cathode is 4" then the anode must be 8"?

Is it alright to use silver wire for the anode and copper wire for the cathode?

That said, You are right on the relationship between current(mAh) and particle size. Though I'd also point out that there are physical limits to the minimum potential size a Colloidal Silver nano-particles can possess which I believe is important to recognize prior to committing to a given process.

ie, lower current means longer run-times. Longer run-times means more oxide formation on your electrodes and in solution. And so the trick with such things, is to balance the parameters of the process so as to produce the best possible solution for your needs.

By "oxide" do you mean the black crud that forms on the electrodes?

Sometimes I forget to check the cooking and when I come back I see lots of black crud already. I stop the cooking and just filter out the black crud using two layers of coffee filter paper.  Is it alright to do that or is the CS unusable once black crud is formed?  I have never been able to make CS without black crud being formed.