My res temp is just a few degrees less than the room temp,79f & 75f. you need to keep the temp between 60f-70f, if you use frozen objects be careful. you could end up shocking your plants. If you have enough D.O.(dissolved oxygen) you can somewhat counter the effects of SLIGHTLY higher res temp. My res temp is 75f, but my plants are healthy. DWC is a bitch for me because I am on my first hydro, I am however converting to GH Waterfarm pods. DWC is just more to maintain, for me. I am contantly having to adjust my ph, but that's me!