To make this discussion a bit more practical: the 9-foot head in my example is 5 feet of static head plus 4 feet of dynamic head. The other two circuits are nearly zero static head as they are TPR circuits with a flooded suction pump: let's call them 1-foot static head each, and 3-foot and 5-foot dynamic head, respectively. I'd like the TPRs to flow 1000 GPH each, and the waterfall one to flow 2000 gph:
- TPR#1: 1000 GPH at 1-foot static head plus 3-foot dynamic head,
- TPR #2: 1000 GPH at 1-foot static head plus 5-foot dynamic head, and
- waterfall: 2000 gph at 5-foot static head plus 4-foot dynamic head.
Assuming that I've accurately calculated that 2000 GPH through the waterfall circuit creates a 4-foot dynamic head, and that the two TPR circuits will have ball valves to restrict flow in order to bring their total head up to 9 feet, then am I correct that the pump has to be able to provide 4000 GPH at a 9-foot head?