If it's a March pump, you throttle the pump with a ball valve on the outlet. With a 2-tier, you can either have the kettle down low, gravity drain to it and use the pump to xfer the sparge water. Or, you can have the mash down low, use gravity to move the sparge water and the pump to xfer the wort up into the kettle. I can see benefits of either setup.ebhomey said:How does the two tier work? i get the sparge part but how do you control the slow outlet of the mash into the boil? pump? i have a pump but it dosen't run that slowly???