I have a 16,000 gallon kidney-shaped pool, with jacuzzi tub overflowing into it. There is one return line to the tub and 3 to the pool. All lines are 2 inch, except from manifold (lines from skimmer, pool drain, tub drain) to pump and pump to filter where the line is 1.5 inches. The pump is a single speed 1 hp and the filter is a 24-inch sand filter. There is a heater as well that I never use. 14 cents per kWh in the second tier.
Okay, I was thinking to update my motor or pump/motor to something efficient and was thinking of a 2-speed type. When looking at the Whisperflo 1hp 2speed performance curve, I see that at 3450 rpm the pump can deliver the gpm for high heads quite well. However, to be energy efficient I have my eye on the lower speed (half of full speed), but the curves do not go above 20 feet of head. I assume that my effective head is perhaps double of 20 feet. If my assumption is correct, then the lower speed would never move my pool water. Is this a correct interpretation? Thanks!