will putting a hose on the intake of my pump decrease the flow rate?

Depends. The reason it depends is, it depends on what is the diameter of the
hose, are there any kinks in the hose? The length of the hose, etc. These
all affect the ability of the pump to draw in water.

In general, yes it probably will restrict the flow rate of the pump.
Question is by how much, and is it acceptable. That is not answerable with
the information you've provided, so the best answer is something one of my
professors used to say. "Try and find out, then report the results back to
us"

Snooze

Yes. Pumps are more sensitive to the negative pressure of an intake line
than the positive pressure from the outgo line. Short lengths of pipe will
have minimal effect. Larger intake lines will reduce the flow restriction
and minimize the effect. My external pumps all have pipe going from the
pond to the pump, with the minimum distance being about 20 feet.
--
RichToyBox
http://www.geocities.com/richtoybox/pondintro.html

Yes it will, but you're more likely to burn out your pump by restricting the
input than by restricting the output. Restricting the output should reduce
flow and at the same time reduce power consumption.
--
derek

Thanks, I like the noise that my waterfall produces and decreasing the flow
rate would diminish the sound.
So thanks for your replies, I will use the other solution of a smaller
existing pump to create the circulation I need.

A general rule of thumbe for restricting your pump it to always restrict the
output, not the input. Restricting the input can damage your pump.

BV.

You should add more valves on the outlet to divide the flow . Let the
pump push only as much as it takes to reach the top of your falls by
diverting pressure somewhere else. You may pump more water but for
less wasted pump life and power

If I understand you correctly, you're suggesting that you should run the
pump at full flow to save energy. This isn't actually the way these pumps
work. If you restrict the output they use _less_ energy than if you run
them wide open. Less wasted pump life and power. It seems
counterintuitive, but it's true.
--
derek

So as THD increases power use decreases?

THD? TDH? Total Head, anyway. Yes. To the point that it should use the
least power when you have sufficient head to get no flow.

I tried to find some of the old discussions on this topic. About the best I
could come up with is a thread:

http://groups.google.com/groups?q=po...aol.com&rnum=1

If you have trouble with that link, google for 'pond pump power consumption
head "power factor"'. Read anything by Rod Fairlee.

Whatever happened to Rod, anyway? He seems to have stopped posting about
the same time I did.
--
derek