Hight temps will rot your roots and turn them nasty slimy brown. Fox Farm nutes will turn them brown too. I think Techna Flora has a product that does the same. I agree with Illegal Smile...if it smells bad, looks bad, and your plants health is bad, then it's real bad. Other than that just let the roots do there thing. I stopped looking at mine so much. I mean, I put alot of effort into lightproofing my tank to keep cracking it and looking at my roots letting light just flood in. I know I coulod look when the lights were off but then I couldn't see. It finally sunk in to me that roots like to think they're in dirt and it's dark and cold in dirt.