microbubbles in rsm 34

[mr.tangman]

I have spoken with steve several times about this matter and the bubbles still persist. I have narrowed it down to the return pumps but am unsure of which one. Could there possibly be a break in the seal somewhere inside the pumps? Because there is nothing blocking the flow to the pumps.

[redseasteve]

It's highly unlikely. However the first thing to do is turn the pumps off one at a time and see which is the culprit. Then remove it, reassemble the impeller and try it again. Check that air is not being drawn in to the nozzle outlet through the creation of a venturi (best to rotate the nozzles a couple of times to free any trapped air). If the trouble persists then your lfs may need to swap the pump for you.