Advice on the Mag Pump 1800 vs 2400

[Chin_Lee]

I'm looking for advice from persons with experience with water pumps. I was comparing the two above noted pumps on their website http://www.pondmaster.com/ and according to their specifications:
- at 0 head, the 1800 is pumping 1800 gph and the 2400 at 2400
- at 12' head, 1800 = 750 gph, 2400 = 800
- at 13' head, 1800 = 660 gph, 2400= 650
- at 14' head 1800 = 560 gph, 2400=500
The output on the 1800 is 3/4" NPT and the 2400 is 1" NPT.
I've emailed EG Danner several days ago but no replies. So my questions are:
1) is the increase output at the higher head pressure for the 1800 due to the smaller output size?
2) will the 2400 have a higher gph at those heights if it was reduced to 3/4 output?

Any insight would be appreciated. Thanks

[Bryan]

One thing you should consider in regards to the Mag 2400 is the power draw. I believe it's something like 350 watts.

[Chin_Lee]

according to the website the wattage is 265W for the mag 24 and 145W for the mag 18. But it still intrigues me that the 1800 has a higher output at the higher heights.