s.hutch@mindspring.com asks:

>Has anyone have any insight on using a PIC to control a set of >electrodes
>(copper,silver) used for swimming pool sanitation? The >marketed versions
>of these "mineral ionizers" are expensive for what >they really need to do.
>You are paying for fancy packaging of a basic >circuit. The DC current
>polarity reverses every so often ( I do not >know the time interval) and
>the current is limited to regulate the >rate at which the ions are  "worn"
>off of the electrodes. I do not >know the quantization on this either. I
>was going to purchase a >replacement electrode ( <$100) and design a
>conroller if I could find >more info on the physics of the ionization. I
>figured I would check >piclist to see if anyone has already visited this
>area for a PIC >project.

>hutch

Hutch,

Most such electrolysis electrode packs are NOT made of copper or silver but
of oxide coated titanium or niobium (columbium) electrodes. The oxide
coating is generally ruthenium oxide where the objective is to generate
chlorine. This type of electrode is also known as DSA (R), aka
"Dimensionally Stable Anode". Copper or silver, when used as an anode will
erode, shedding copper and silver ions into solution. The coated titanium
electrodes will not do this. The purpose of polarity reversal is merely for
scale reduction. It will not prevent the eventual destruction of copper or
silver electrodes. I would think that you could achieve the polarity
reversals just as well either manually or with a mechanical timer switch.

I use such electrode packs in my research on electroflotation. I would be
happy to answer any questions that you might have concerning these electrode
materials.

Regards,

Brad Hernlem

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