On Mon, 25 Jun 2007 09:31:35 CST, Kurt wrote:

MagDrive. The higher the head the quicker the flow rate drops on these.
Thus, check a flow chart: http://www.justliners.com/suprememagdrive.htm
For every 10' of pipe (and I'd recommend 1.5") count as 1' of head, so
according to this chart if you have 5' feet from surface to top of
waterfall and 10 feet of pipe you'll only get 950/gph.

This may be okay if your waterfall/stream is narrow and the pond is mostly
plants with a few fish. Now if your head is only 3 feet this pump should be
fine, otherwise, imo, go with the 1800 gph. ~ jan

Kurt replied:
Very informative post, thanks. I can see now how I'm losing efficiency.

Yea.... I forgot those blasted elbows. Though we here use the sweeps for
better flow.

Okay, RTB (or anyone), many moons ago there was discussion in old RP
regarding pumps needing a certain amount of head/back pressure to work at
their best. Is this still correct and is that also true of mag-drives?
~ jan
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Zone 7a, SE Washington State
Ponds: www.jjspond.us