Quote Originally Posted by pauster
If I chose, say a 1/2 HP Hayward Northstar SP4005NS, I could get 70 gpm of flow. Since it is a .37kw, this would be a 3.36 amp motor ?
No, kw is euro units for horse power, it does not include the efficiency of the pump. The 1/2 HP northstar uses the same current as the 3/4 HP so no energy savings. In fact it is worse since you need to run it longer for the same turnover.

If you really want to save money, then I would suggest a 2 speed pump. Your savings could be as high as 30%.