A system includes a flow inlet conduit. A primary conduit branches from the flow inlet conduit for delivering flow to a set of primary nozzles. An equalization bypass valve (EBV) connects between the flow inlet conduit and a secondary conduit for delivering flow to a set of secondary nozzles. The EBV is connected to be controlled to apportion flow from the flow inlet conduit to the secondary conduit. A secondary equalization valve (SEV) connects between the flow inlet conduit and the secondary conduit. The SEV is connected to be controlled by drain pressure (PD) to apportion flow from the flow inlet conduit to the secondary conduit.