Best way to clean a filter

[Redbled]

One of my filters is running slow. We had a lot of hard water at our previous residence. What is the best way to clean the impeller, as I think that is where the problem lies?

 

[Sky042]

I've used vinegar to remove hard water deposits.
But be forwarned if you do this only do the impeller. Don't do the whole filter as that'll cause you to recycle the tank.

Also sometimes the impeller bushings just wear out. I had a hydor power filter that wore out on me in 6 months(sand tank) but the emperor that replaced it has been strong for the past 8 months.