Depends on the type of pump.......If its a mag-drive you can still just choke an output valve to what ever you want it to do. Or you could get fancy with a re-circ loop and extra valves.....basicly take the output of the pump, install a "T" fitting with a valve on each output...one going to your end point...the other looping back into the inlet of the pump. You can play with the valves to get what ever result you want. On startup when the pump is priming itself, the loop valve would of course be closed. The rest of the time when you want to controll the flow you can open the loop valve more to get less flow....and you can close both more to get more pressure...