Wow. It might still be too early to tell, but initial results show that adding the fans to the tank seem to help quite a bit.
The tank went from regular flux to holding steady.
I’ll probably add some logic to the circuitry to turn the fans on/off based on tank temperature. I don’t want the fans lowering the temperature too much at night. Maybe I’ll have them come on at 80 degrees and go off if the tank drops below 79. Then, if the fans can’t keep up, the chiller will kick on at 81.