Aquacomputer flow meter, put it on pump output or input?

[almighty15]

As above, have my flow meter now and not completely sure where best to put it for the most accurate results?

I'm thinking to put it on the return line back to the pump as that'll give the worst case flow rate?

 

[almighty15]

Got the sensor installed and I'm under 1 gallon per minute!!

So I have a couple of Laing D5's coming in the post which I'm planning on using or should I keep my DDC's and run them in serial to try and get my flow rate up?