Tips for pentagonia grandifolia re. damping off

[KarenRei]

I should soon be getting an order of seeds, among them Pentagonia grandifolia. The last time I ordered them, I was thrilled to get nearly 100% germination (which, given the small seeds, was a lot of plants!). But that was then - slowly, one by one - followed by 100% damping off  :Þ

Any tips for preventing damping off in sensitive species?  I'm thinking about:

1) Going with a 100% inorganic starting medium, and only moving them to soil when they outgrow it. Frequently moistened sand / perlite, so it drains well?
2) Dissolving captan in the water that I water with (my captan supply is old... will it still be functional?)
3) Keeping at least some of them in a humidity bag well past the germination stage (in case insufficient humidity was the cause, rather than fungus).  My plants grow in an area that's high humidity, but not "near 100%"

Do these sound like good ideas?  Any other suggestions?