artships wrote:

On further reflection, I seem to be suffering from the erroneous
impression that, for pond distances (5-15 feet), a hose needn't be any
larger in diameter than the pump outlet, as if we were discussing
electricity, here. Although I've doubled the diameter of the hose over
that of the original, there is only cheapness keeping me from buying
another even larger hose.

You're absolutely right. Surprisingly, the outlet size has little effect on
the amount of water you can pump through a large enough hose. There is a
limit to how much increasing the size of the hose will help, but if you
take your hose, straighten it out and measure the flow, and it's
appreciably less than your pump puts out without a hose, you should
probably use a larger hose. Then, when you run the plumbing, make your
corners as gentle and as few as possible, because every corner lowers the
flow.

Or you can just consult someone who knows how to calculate the head loss due
to your plumbing. We used to have someone here...
--
derek