circulate water
I use a small water pump to circulate the water through the clear hose, I realize that the hose isnt a great conductor of heat, but it seems to work pretty well. The pump i have has a stainless steel housing which i purchased at harbor frieght, I also purchased a DC motor controller to slow the pump down. Its a pretty powerful little pump @350 gallons per hour and only cost $27. I dont leave the pump on all the time, i only turn it on once the amp draw is at 30. The DC motor controler should legthen the motor life and it deffinately makes it alot quieter. At full speed the little pump is a bit loud.
2006 Ram, 5.9 cummins HO. 4 cell design, 1.5 LPM@30amp, 24.3 MPG