My temps in my water stayed 75+ the whole time I grew my last grow, in my signature, it wasn't until I WAY over-nuted them that I had problems at the very end. My grow before this I used to use frozen gallon jugs of water and found it to be to much of a hassle to deal with and the ice was shocking my roots. I still don't have a waterchiller but my nutrient line seems to keep them happy. A little discoloration from the nutrients though. All and all for what you have to work with you seem to be doing fine. Just don't over think it, like one of your comments said I think she needs more nutrients after you fed her and I'm all like WAIT til next week and get a ppm meter because more IS NOT always better. These nutrient lines are concentrated nutrients. Also why is your light so far from your plants, is that a metal halide bulb? If not get a 400w MH bulb for vegging if you have an adjustable ballast. Just my 2cents.