Ok guys, just to clarify, this is how I connected things up, clear hose to metal feed tube, clear hose to metal return tube on top of the engine as you look at it, both ends of tube in the jar full of DP.
So my thinking and why I asked about the air bubbles which incidentally were the same from start to finnish was I thought that the fuel going in from the jar and the fuel being returned to the jar would be bubble less, just solid fuel. But although the fuel was solid fuel being sucked from the jar, the returning fuel had lots of bubbles in it , I was thinking that because the fuel was basically going around in a loop, it would come out as it went in.
Regarding swapping hoses, the only one I have changed is the short feed pipe to the inlet to the pump and clamped with proper quality squeeze clamps.
Regards.and thanks for your input.
John