I have a reef octopus water blaster 5000 which has a circuit that starts the motor at slow rpms and builds. I'm running a chiller and UV sterilizer with it. There are a bunch of different pumps out there that have the slow start. You just need to do research on the ones you like and check flow rates to get the correct pump for your chiller, remember to take the height and distance of the piping into account for correct flow rate.