[bayreef]

i understand so unless one is slipping then all 3 should move at the same speed. A Rep from Tunze said the device they use to cut down the impellers could be the cause but not likely. I have one impeller that no matter which pump it is in it pushes more water and another impeller that no matter which pump it is in always less flow. No visible difference. Tunze sent me a prop incase i had the "uncut" lol version. The new prop does better than the weakest one i had and i am pleased along with the standard mod on a 6045 (for now). I do have two different versions ( one has a round cord and the other is flat) this was never a problem having a flat cord, but they were just not able to get enough flat cords, after production had already begun. I think the flow is more spread out even with the standard mod, it is more even with less ridges or "veins"., just broad flow.