[stymar]

Looking at the guts of a salt water pool chlorinator, one sees
the equivalent of a battery charger with a few extra bells
and whistles.  The people who market these devices insist that
the electrodes must be palladium coated.  They sell these
at an exorbitant price.  The various articles (wikipedia and others)
just specify an inert metal such as stainless steel as the
electrodes.  Titanium is also pretty resistant to salt water.
Is there any overpowering reason that a palladium coating is
needed to make the electrolysis work?

[Arkcon]

Under the reduction / oxidation conditions found in an electrochemical cell, may metals will wear away rapidly, releasing their ions into solution.  And those ions have unpleasant effects on pools and people.  Its definitely worth shopping around for the best price, but you will need something there better than stainless steel.  For example, a nickel alloy, or maybe a friend in the electroplating business will re-plate some old electrodes for you.  I knew a guy who'd gold plate terminals for anyone in-house who asked.  The gold plating didn't look smooth, and it was so thin, you couldn't handle them too much.  But for corrosion resistance, that was just what was needed.  Note:  you can't use gold or platinum in this case, those metals are attacked by chloride in an electrochemical cell.

[stymar]

Any thoughts on Titanium?  The Russians like to build submarines out of it.

[Arkcon]

Any thoughts on Titanium?  The Russians like to build submarines out of it.

The hulls of submarines do not have a DC current flowing through them, so are not exposed to the particular oxidation potential the the electrolytic cell is.  I haven't heard of titanium as electrode material -- it may be too sensitive to oxidation by current, by charged chloride species (like gold and palladium are, even though they endure just fine in salt water), too low in conductivity,  or simply to hard too fabricate.

[fledarmus]

Although titanium does make excellent welding electrodes for inert gas welding! 

[stymar]

  Thank you very much.  I will continue to investigate alternative plate materials.  I really appreciate the advice on the by-products of the breakdown of the plates.  Carbon is an order of magnitude less conductive than steel, but with a bit more voltage might do the trick. 

[Arkcon]

Theoretically, carbon is non reactive.  However, when I tried to use carbon rods from dry cell batteries as electrodes for electrolysis, the anode.  Either the oxygen formed, or the current gradually pitted the rod.  I think I gave up when the rod began to be consumed.  There may be batter quality carbon electrodes than the carbon rods in batteries 'tho.   But you will have to be prepared to pay a premium for those, and they still might wear out.