I would not want to use anything less than a 500 gph pump,i made my own block that is 5/8 flow all the way and i use 5/8 lines, i found that the larger flow works better. 750 duron @ 1000 mhz, 1.85 core, 120 watt/24 v pelt ,500 gph pump, evap cooler= 27f at idle. works for me
