Thanks that is really helpful - I think the installer like many others are confused and think one pipe system means a PITA - The potters buy guy said that just earlier
The pipework I have is wide bore so 3 inch pipework so I thought thats why the pump was specced to be so powerful
When I ask about the way to double check the right size I get told "other factors" which dont help - So is it really a guessing exercise or is there some sceince to tell you if you need a 6m / 8/ 10m pump
EDIT - I think my pump runs on one speed only so there is no way to change it - At leat thats what the manual says
https://www.dabpumps.com/sites/default/files/2016-03/VA_VB_VD_TS_ENG.pdf