I am replacing a submersible pump in an existing pond/waterfall with an
external pump and pressure filter. I want to direct all of the flow to
the waterfall, i.e., the output from the pump and the filter is to go
to a single 2" pipe that supplies the waterfall.

How should the ball valves be positioned to correctly control the flow
to the pressurized filter and the flow of the waterfall?

Can I tie the output of the pressurized filter back into the line
feeding the waterfall?

Should I tie the output of the pressurized filter in before or after
the valve that controls the waterfall rate?

Here is a diagram of what I am planning. Is this correct?

_____________________________________
| ___ ___ |
| +----------|_X_|-----+---|_X_|--+-- Waterfall
| | ^ | ^
| | Valve to control | Valve to control
| | filter rate | waterfall rate
| | ______ |
___|___|___ | |__|__
| out in | | Pump |_____|----+
| | |______| _|_
| Pressure | | |
| Filter | |\| Check Valve
|___________| |_|
|
_|_
/___\ Strainer

Thanks