[[The point is that you need to have a low resistance path on the input of the pump.]]
-just saying
-putting a pump up and one down cuts resistance in half\50% does it not ?
-where I,m at loss is that it's greater than 32'[I think] is the max any pump in the world can draw [@sea level?],so how -say a 2psi drop on the block's\tube relate[down-up]- scaled down in a closed loop on these low pressure pumps.