Please check my filter and pump calculations

[mas985]

It will be very difficult to find a pump that will have a flow rate that low. Even a two speed pump is likely to exceed that at low speed. So my suggestion would be to look at 3/4 HP two speed pumps as these are about the lowest HP and flow rates you can get on the low speed. You will get about 70 GPM @ 50' head on high speed and 35 GPM @ 13' head on low speed. A bit higher than what you want but it won't cost you too much to run either.

In addition, the Whisperflow 1/2 HP pump has about the same current draw as the 3/4 HP motor. I think it is acutally the same motor and they use a different impeller. So it probably does not pay to go down to the 1/2 HP pump as it will cost the same to run.