Originally Posted by Ganoderma
Water temps below 70f are NOT always needed! The environmental conditions where you are growing will affect if you need to lower your nutrient solution.
I have never had to lower my waters temp in a hydroponic system.
You need to differentiate between roots-in hydro, and roots-out hydro temps. Roots-in systems are much more sensitive to temperature than roots-out. It's advised to keep your res at 79F and below, so you stay out of the potential danger zone.
Roots-out systems can tolerate much higher temps, as previously mentioned in the thread. The OP is using a roots-in system, so without going sterile res, it's advised to keep the temps low.
I've been running non-sterile, roots-in DWC for 15+ years, and I assure you I know exactly what I'm talking about. lol