Return Pump Longevity?

[NanaReefer]

I unplug my return pump during water changes. It was suggested to me that by doing so over time this will cause the impeller magnet to swell, if I'm understanding correctly.
Does this actually happen? Need I invest in spare impellers?

 

[mcarroll]

The only thing that should make an impeller swell is if the plastic coating on the outside of the magnet cracks or is otherwise compromised and salt water gets into the magnet which will then rust and swell.

As far as investing in spares, I would say yes if your pump or impeller is somewhat rare. If not (like most major brands) I would wait until you need it.

Random stuff can happen, but I don't think this should be a major concern with any major brand pump.

 

[laverda]

A lot depends on the pump your using. External pumps tend to last much longer and require less maintance then internal pumps. With out naming names there are pumps currently on the market that fail within 6 months fairly often and others that should last a lifetime with a little care.
If your using an internal pump and run it dry, it will destroy the magnet.

 

[mcarroll]

External pumps tend to last much longer and require less maintance then internal pumps

I know that's supposed to be true, but my experience has been the opposite. External pumps seem to be just a susceptible to dying inside of five years as any other pump.

And what seems to take out internal pumps as much as anything in my experience is the insulation for the power cord receding from the pump (exposing the wires) - not failure of the motor block or impeller.

Most external pumps do carry other advantages, however.