The bottom of my 30,000 gallon fish pond is full of sludge and fish s^&t. I
want to try to make a venturi style sump pump. These pumps are extremely
simple. They work by using a high pressure water jet to move a large volume
of water at low pressure.

Here's a little bitty one:
http://www.aquaticeco.com/index.cfm/...d/2556/cid/750

Here's one for a basement sump application:
http://www.pumpbiz.com/products/inde...&series_id=820

Here's one moving tens of thousands gpm:
http://tech.praqua.com/pdf/nb/2001/MayJune01.pdf

For my job, I have a 10 gpm 400 psi piston pump (tractor PTO driven hypro
model 5200). I have a 2" suction hose fifty feet long. I'm thinking of
building the pump into a 4" plastic sewer pipe Tee. The bottom of the Tee
would be the suction inlet. The right of the Tee would have the high
pressure water nozzle. The left of the Tee would be the outlet. It would
look just like the unit in the first link only a bit bigger.

I need design help. Specifically what size orifice should I try for the high
pressure outlet. And where should the orifice be located. Also 4" ID of the
tee is probably too large, what would be the best ID to use? Any other
suggestions?

Karl