Unless I got your current pump curve wrong, I think your flow today with the Hayward pump is closer to 60 GPM based upon the Hayward pump curve @ 45ft of head (rounded up): http://www.haywardnet.com/products/d...m?ProductID=10

That Hayward pump has a BHP of about 1.24 because it is a max rated pump.

I am not quite sure how you did your calculations for the new pump but this is how I would do it. You current plumbing is defined by the head and GPM no matter what type of pump you use (power formulas cannot be used between pumps because efficiency curves are different). So first you need to iterate this formula for a solution that falls on the new pump curve:

New GPM = 60 * sqrt (New Head/45) where new GPM & Head must fall on new pump curve.

So for the intelliflow here are my estimates for each of the RPM settings:

3450 RPM - 85 ft head - 82 GPM - 2.6 KW - 31 GPM / KW
2070 RPM - 30 ft head - 50 GPM - 0.6 KW - 83 GPM / KW
690 RPM - 3.4 ft head - 16.4 GPM - Hard to read power

Each of these should fall on their respective curves.

This pump has a pretty high head at the top setting so you may not use it much. It also costs a lot so the payoff may be longer than a two speed pump.

A 0.75 HP Wisperflow would have the following economics:

High Speed - 55ft Head - 65 GPM - 1.7 kw - 38 GPM / KW
Low Speed - 14 ft head - 33 GPM - 0.5 kw - 66 GPM / KW

Not as good as the other pump but payoff may be sooner.