I've just given you the instruction sheet

Your
pump has a pressure switch - when fitting a
Varistream you have to take the wires off the
pump pressure switch as the instructions.
Your
pressure is now controlled by the Varistream
However, depending on the hose diameter or length and pole height - your Varistream needs to be calibrated to control the pressure cut off point.
When this has been set then your
flow can be altered to whatever you require.
There are two settings
PRESSURE calibration and
FLOW setting.
Once you've got them right you'll hardly ever need to change either. Normally your pressure setting might need increasing in cold weather a bit and reducing in hot weather but not by much.