brown roots dont mean root rot

it depends on your fertz. clear fetz, white roots, black fertz brown roots. and also, my res temps are well above 68, and plant is kicking ass!kiss-ass

True on the root color, and yes, you can successfully grow with res temps in the high 70's. However, high res temps make the plants more susceptible to problems IMO. High water temps means less DO and less DO means anaerobic conditions and anaerobic conditions are conducive to anaerobic pathogens, which are probably always present to some degree.

With high res temps, any little problem in the res can turn into a major one much easier. High res temps is probably why H2O2 has become so popular as a preventative measure IMO. Keep the res temps down as a preventative measure and you won't have to rely on other additives.

Just my opinion...