Quote Originally Posted by herbie the love bud
You think you have root rot because the roots are kind of a brown color? That could be normal depending on the nutes. Lots of different nutes will turn your roots brown, some will even be a little sludgy (organic nutes) but that is not rot.

If you water temp is under 80 degrees and your bucket is black, I don't believe u have rot. Just don't. Keep growing my friend.
Listen to herbie here, the chances are against you having root rot. Are you using any Liquid Karma? Aside from organic nutrients, LK is a huge brownifier (like my word?) of roots. Like he said, they can even turn sludgy after only a few days and it is not necessarily a problem.

If you are still worried, try a little H2O2 as suggested.