"Christian McArdle" wrote in answer

You should buy a pump with negative head capability, as you may find the
flow switches are unreliable with such a low head. A negative head unit
has
a separate pull cord to kick start the pump.

Fine, but what's the solution to a pump which won't switch off reliably? My
Monsoon pump is excellent and robust (metal and brass!), but tends not to
switch off when the shower or tap valve is closed. I often have to 'flick'
the monoblock tap quite hard on and off to get the pump to stop, on both H &
C. Stuart Turner (user instructions) thinks this is due to sticking flow
switches on the pump, but the test with a small magnet shows no problem.

regards,
mutley