" wrote:

I am also no expert, but I would expect that the horse power needed to
drive the pump would be the key. Fewer gallons per minute at higher
pressure would work as well as higher flow at lower pressure.

Before I built a venturi water pump I would think about draining the
pond and using a front end loader. Could you start at one place and
clean out to firm footing so you don't get stuck? Do you have a backup
plan if you do get stuck?

If you do build a venturi pump, I would scale up from a jet water pump
for the design. Probably use a smaller orfice since you are not using
a centifical pump and boot straping the output . I would also
consider another jet in front of the inlet directed to stir up the
muck. If you put a screen in front of the inlet, you could use your
trash pump to help suck the stuff through.

Dan

I'd think "hydro-dredging" would be a lot easier than draining and using
heavy equipment, but I thing you're over engineering it with the venturi
pump idea.

Make an intake nozzle assembly to fit the suction line of your trash
pump out of sheet metal that flares out and tapers down to a long
rectangular inlet with the narrow section the same width as the solids
rating of the trash pump. Weld pieces of 1/8" rod across the opening at
the same spacing to provide support and act as an inlet screen.

Mount a suitable piece of pipe perhaps 6" back from and parallel to the
suction opening. Drill a series of holes along this pipe to act as
nozzles to shoot water back at the suction inlet. Use appropriate
fittings to provide inlet water to the jet pipe from a source inline
with the suction hose.

Cable tie your hoses together and then use your high pressure pump to
provide the jet water to loosen the sludge and push it towards the
suction and the trash pump to suck the muck up to your settling pond.
Drag the sweeper around the bottom with the hoses as needed to clear the
muck.

Ok, so that idea is over engineered as well, but I think it will work
better.

Pete C.