Just thought I would post a some pictures of brown roots that were caused by excessively high
nutrient water temp. If I remember correctly the nutrient temp was in the upper 80's and low 90's at the time of the pictures. They are the roots of the strawberry's that I grew 2 summers ago, and the pictures were taken in either late May or early June. Our temps in early June reach in upper 90's and by late June they are in the 100's (I grow everything outside). I sent the pics to General Hydroponics tech support, who told me it was caused by the nutrient temp. That's when I first learned that the nutrient temp was important.
I then froze blocks of ice to cool down the nutrient solution with, I then saw new roots coming out a nice white like they were supposed to be. I needed to add ice blocks twice a day, once in early morning, and again in mid afternoon. Even so, the nutrient temp would fluctuate and I couldn't keep it within range constitutionally. By early July the daytime temps constitutionally reach the 110 degree mark, and I was simply not able to keep up with freezing the amount of ice I needed. With all the containers of water jam packed in the freezer absorbing all the cold, the ice creme was getting soft and melting (even on the highest setting). So I gave up on my first summertime attempt at hydroponics.
I know you are growing inside and are very unlikely to see anything like those nutrient temperatures, and I didn't post the pictures to scare you. But I had the pictures, and thought it might be helpful to see what happens when the roots of a plant are constitutionally subject to high temps for future reference.