Well,
I got a chiller and there was a profound difference in my grows!!!!
For ever 10 degrees you are above 68*F you have 25% less O2 concentration in solution, but the killer is that same 10 degree increase in water temperature boosts your roots oxygen demand by 100%!!!!!!
My rez is set at 66*F and with a 2*F differential, so it actually starts chilling when the temp hits 68*F. Why do I have it set so low?? You need your rez temps below 70*F to prevent the growth of root rot, root rot cant survive in water temps below 70.
Frodo