Usually they turn brown first, then comes the slime. You have the beginnings of root rot. I am suffering from this as well, with my temps getting up to 76 with my HPS on. I have been using 2 liter bottles of frozen water and cycling them every 6 hours of day time which keeps the res temps between 60 and 70. I would try this, and also use something to spray any slime or decayed material out of the root mass, as if its still in there, it will keep eating new roots that are produced. H2O2 is a decent fix, but don't go too heavy on it, and it will also likely gunk things up because it will kill the baceteria and will then in turn become a wicked slime all over everything in your res. Battling root rot is a real bitch, so be prepared to spend a lot of time in your garden. Good luck! :thumbsup: