Try what these guy say. It's the first thing you look at.

From what little I can see it might also be Cyanobacteria. If the normal treatment does not seem to work or makes it worse then you need some Physan20. It's too late for your plants but you will need it to clean up all the nasties.

If it were light leaks you would have a good amount of algea and I don't see it. Looks more like heat and neglect.
LOC NAR on probation Reviewed by LOC NAR on probation on . browning roots in hydro my friends hydro system is in about week 12 of flowering and is not doing well at all.....3 of the plants have died (out of the 5) and now the two left...one has browning roots....there was alot of light showing through the side of the bins which wasn't fixed till about a week ago....I'm guessing that the roots have started to rot and wont make it...but they also say that it could be one of the chemicals they are using which is dark brown and could be staining the roots(but i dont think it Rating: 5