You need bene's..
Look at the top 2 pics in this thread
See the bottom brown stuff and the bucket is perfectly clean? Thats bene's! They have colonized the bottom and are cleaning the stuff up and protecting the roots (im assuming thats whats going on). I have only topped off that bucket for going on 5 weeks now. I cleaned the bucket with Isopropl to kill everything, then rinsed out and added nutes with bene's. This bucket has
Great white and a little Guardian MY (before I got the
great white, its all good stuff). Some enzymes would help as well :)
You gotta start super clean or your fucked, plain and simple. If your using standalone buckets, you can always sterilize a bucket, add nutes, and just move the netpot lid from one tub to another. If you can lightly rinse off the roots and get as much crap off of them as possible. Try to avoid H2O2 if you can. It kills all of the little guys and then you get stuff eating the little guys and there is sure to be something that decides your roots taste good too. lol. Sorry Little stoned at the end there, hahahh.
Good luck! :)