I'm using a 10 gallon tote with 5 gal of ph' d tap water with 2ml of hydrogaurd per gallon of water no nutrients I'm hoping it's not the notorious cyanobacteria I've been reading about
IDK, honestly. The roots looked nice and white.
If all you're runnnig is h20 and hydroguard, it could be the hydroguard. Like I said I've seen a white, slimy, fungus stuff on my roots before, like that, that went away when I cut back the HG. Any chance of getting a clearer pic? HG should consume any of the extra nutrients and biological matter bacteria can live on, but introducing tap water keeps adding fresh bacteria, so it could be colonizing. The rapid rooters are also inoculated with bennies. What temps are your res's running?
Here's a picture of bacillus amyloliquefaciens, the bacteria in HG, and the article it came from, most of its over my head. Pretty much talks about the good bacteria forming a colony barrier around pathogens. The pic shows it. It's a white slime consistency. It's a good thing.
http://journal.frontiersin.org/article/10.3389/fmicb.2014.00636/full
When you took it out of the rapid rooter, you should have put it straight into the hydtoton, take the rapid rooter out of the equation. It will still be fine, don't mess with the plant anymore, it's too young.
It's your choice, let it ride or go nuclear and either stay sterile or reintroduce new bennies.