Another idea N+1
 

I was wondering what the faileure mode is.

If the pump - run two in parrellel with check valves ?

If the jet maye two or better still a staged system one on at say 10 psi or what ever is 1/2 the max flow needed and the second at say 15 psi providing the other 1/2 of the flow . If one system fails you still have 50% of the flow worste case and tune accordingly on the conservative side.

I assume this has been done ?

There must be a problem other than it costs twice as much ?

Thanks Charlie

What most people fear is failure of the high pressure pump. Something similar to your suggestion would be to have two high pressure pumps feeding a common reservoir. The effort to pressurize the reservoir woulf be duplicated, but if one pump failed the other could support the system.

One most common reported problem with the 2d system was " loss prime" once air is sucked into the delivery line. The pump will run contiuously to regain pressure but the trapped air has no where to go until the next opening of the HSV valve.

When you plan your system, try putting some baffle into the water tank or have a small accumultor tank just below the main tank.