Is impeller ring on Hayward Super II needed?

Discovered that I forgot to reinstall the impeller ring on my Hayward Super II (2hp) pump after replacing the seal. The pump seems to be working fine, with no noticeable vibration or unusual noise. I notice that smaller Hayward Super II pumps don't even show an impeller ring on a parts schematic. What does the impeller ring do, and is it really necessary?

It increases the efficiency of the pump (i.e. reduces re-circulation losses) and it also reduces axial/radial loads on the motor shaft. So although you don't see any difference now, it could possibly reduce the life of the bearings in the motor.

Thanks for the explanation, Mark. I replaced the ring today.

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