Thank you again frankchong. I do not know where I got the idea that the power consumption would make a bell curve. I must have been thinking about the plot of efficiency against flow.
Many manufacturers do not provide a recommended head and only give a plot of Q/H from the point where Q=0 to the point where the curve breaks near H=0. The flow is often x axis and head is y axis. Like this...
http://www.aquaticeco.com/index.cfm/...mages/iid/7692
This graph is for Wave pumps from the Aquatic Ecosystems catalog. With no other information available, you would anticipate that the sweet spot will be about one-third up the curve from the bottom - about 125 gpm and 18 feet for the HSW1. Is this correct? That is a very useful rule-of-thumb.
-steveh op