It's an oxidizer, there are a couple of current threads on it. However, I think those people are using it in their hydroponic grows.. crap, I can't remember now.
I've never used it on soil, only on wounds, dirty mouths, and for fish and corals.
You might want to check your overall humidity, watering practices, air circulation and all that if you really think it's mold or something like that. I'm basing my suggestions on your description of what you see, it could be a fungus, a mold, some other sort of spore, but I figure most of these creatures need certain conditions to grow and moisture is usually key. I, too, am a first-time grower, so I'm just reading the HELL out of this site and applying the stuff I know about other things like different plants.
I
have seen some minerals make crystals coming up from the ground that sort of fit your description. I've seen roots on some plants that look fuzzy or hairy, they're easy to see if you root them in water. How do the plants look otherwise?