total greenhorn needs advise

[Tony_agr]

I have this creek on my property that when it rains all the gravel drops out of the flow in this 40' long section before the pond, I can no way use a hand dredge to check the gravel for AU, bedrock is anywhere from 1" down to over 2', I'm buying a 1 1/2" nozzle to process this material. My question is this I made a "Y" adapter with two 1" inlets from a 12v 2200 gph (1875 with the smaller discharge) and a 1275gph, the outlet on the "Y" is 1 1/4" will this be enough pressure and flow ? or do I need a gas pump? if that's the case will a 2" work(158 GPM) if I neck it down to 1 1/2". The creek is going to dry up by late June so I really want to get going.
Thanks in advance for any advise
Tony

 

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[N-Lionberger]

You wont be able to run a nozzle with a bilge pump. A 1.5" nozzle is really small, you would be better off with a #2 shovel. 2.5" seems like the borderline. Don't neck down a pump.

 

[Hoser John]

I'd just get a sluice box and start shoveling to sample both ends and middle first. John

 

[Goldwasher]

you can't get the pressure using a bilge. A 2 inch pump ill barely get you enough suction for a 2" a 1.5 may be ok but, you can do more using a rake and shovel.If you have a pond. Just pump from the pond back into the stream course. Start near the pond and go upstream from there. if you have color near the pond. Just shovel into the sluice for the bulk of it and use the small nozzle to clean cracks and crevices.

All pumps are "necked " down past the pump at the jet. You don't want to add restriction to the intake side you will strain the motor and cause cavitation.