In article ,
~ jan wrote:

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

I'm thinking that it has to be, given how small the opening is, and the
range of adapters they give to attach hoses out.
My line is all tubing (1" I think), but the line to the waterfall is
stepped down to 1/2".

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"~ jan" wrote in message
...
On Mon, 25 Jun 2007 09:31:35 CST, Kurt wrote:

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
------------
Zone 7a, SE Washington State
Ponds: www.jjspond.us

I can remember the discussion, but I cannot find any info showing a need.
There were curves in old AES catalogs, I think, that showed electrical
consumption per gallon, or something like that, which are no longer shown.
The flow curve sweeps downward at an increasing rate with increased head and
the other curve swept upwards at an increasing rate with head. The most
effective use of the pump was the point where the two curves came together.
But, I have not found those curves today.

On Tue, 26 Jun 2007 07:08:59 CST, "RichToyBox"
wrote:

I can remember the discussion, but I cannot find any info showing a need.
There were curves in old AES catalogs, I think, that showed electrical
consumption per gallon, or something like that, which are no longer shown.
The flow curve sweeps downward at an increasing rate with increased head and
the other curve swept upwards at an increasing rate with head. The most
effective use of the pump was the point where the two curves came together.
But, I have not found those curves today.

I was just wondering because I plan to put a mag drive on my lily pond and
it will have maybe 2-3 inch climb and 20 feet of 1.5" pvc to travel thru,
so not much head at all. So I hope it isn't a requirement. ~ jan
------------
Zone 7a, SE Washington State
Ponds: www.jjspond.us

"Kurt" wrote in message
...
In article ,
"George" wrote:

"Paul" wrote in message
news
Thanks for the help, will go to 1-1/2" dia. tubing. I have a diverter
vlv
in there too that splits it up to two filters....

For this size pump, 1.5" should be fine.

George

"George" wrote in message
...

"Gordon" wrote in message
...
I would not go less than 1.5" and preferably 2"
Cheers

Gordon

"George" wrote in message
...

"Paul" wrote in message
. ..
I have a 1200gph mag drive pump. My pond will be approx 1100gals,
is
this enough pump? what size tubing i should use.

It should be enough. I would make the tubing at least one inch in
diameter to maximize the flow and reduce backpressure.

George

My recommendation was a minimum diameter.

George


I've often wondered about all this. My 1200 GPH MagDrive pump has
basicallly a 1/2 or so stock nozzle (if I remember) I've got it stepped
up to 1" tubing to the filter. The pump was designed for 1/2 tubing.
Aren't they all at this size?

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Hmmm, 1/2"? What brand and model? No they are not all that size. The
larger pumps have larger oulets, naturally. Mine is a larger pump. I'm
almost positive mine has a 1.25" output, because I ended up buying
expensive high pressure black flexible hose to fit it (I also wanted the
hose to last essentially forever, and I've got it installed inline between
my pre-filter and my biofilter). You might check to see if yours is
replaceable with a larger diameter nozzle (though it may not be if it is
part of the impeller housing). With less backpressure on the pump, it will
last longer and give you an optimum flow rate for the size of the pump.
But with your pump, it may not make any difference changing out the outlet.
What is more important is that there are no restrictions or reduction in
the hose diameter. It should get larger, not smaller. That's probably all
you can do.

George

In article ,
"George" wrote:

"Kurt" wrote in message
...
In article ,
"George" wrote:

"Paul" wrote in message
news Thanks for the help, will go to 1-1/2" dia. tubing. I have a diverter
vlv
in there too that splits it up to two filters....

For this size pump, 1.5" should be fine.

George

"George" wrote in message
...

"Gordon" wrote in message
...
I would not go less than 1.5" and preferably 2"
Cheers

Gordon

"George" wrote in message
...

"Paul" wrote in message
. ..
I have a 1200gph mag drive pump. My pond will be approx 1100gals,
is
this enough pump? what size tubing i should use.

It should be enough. I would make the tubing at least one inch in
diameter to maximize the flow and reduce backpressure.

George

My recommendation was a minimum diameter.

George


I've often wondered about all this. My 1200 GPH MagDrive pump has
basicallly a 1/2 or so stock nozzle (if I remember) I've got it stepped
up to 1" tubing to the filter. The pump was designed for 1/2 tubing.
Aren't they all at this size?

--
To reply by email, remove the word "space"

Hmmm, 1/2"? What brand and model? No they are not all that size. The
larger pumps have larger oulets, naturally. Mine is a larger pump. I'm
almost positive mine has a 1.25" output, because I ended up buying
expensive high pressure black flexible hose to fit it (I also wanted the
hose to last essentially forever, and I've got it installed inline between
my pre-filter and my biofilter). You might check to see if yours is
replaceable with a larger diameter nozzle (though it may not be if it is
part of the impeller housing). With less backpressure on the pump, it will
last longer and give you an optimum flow rate for the size of the pump.
But with your pump, it may not make any difference changing out the outlet.
What is more important is that there are no restrictions or reduction in
the hose diameter. It should get larger, not smaller. That's probably all
you can do.

George

I agree- need to lose the reduction to the waterfall.

An MGD12 Magdrive Pum @ 1265GPH

Looking at the spec sheet that came with it. Does have a 1" inlet
fitting. Outlet is smaller (no size on sheet and pump is submerged-not
pulling out to check...:-))

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