Just a note. The rust resistant chain in the picture is a KMC Z51RB. Several years ago I got 5 of them off Ebay for about $15. Not all of them had the required master link but I was able to find (after some trial and error) an SRAM PowerLink that worked.

Originally I used one with an 8 speed derailleur but found it to be just a touch too wide. Nevertheless in terms of corrosion it was a noticeable improvement over a standard chain. There was still some rust at the end of the season but not nearly as bad as what I'd normally experience. With an IGH the same chain has virtually no rust at all. I think the action of shifting in a derailleur drive train causes lubricant to wear off quicker. Just on hunch on my part.

KMC now has a 9 speed rust resistant chain available in the states. 45Nrth makes one as well.