Rattle Rattle Arrg!

[ShooterRick]

I replaced 2 impellers on 2 Hydor K3s. They run quite except at start up. They are on a wave timer. Is this common with impeller replacement? Do they just need to seat in? Is this common with the K3s? Thought please. It is not just a click but a a annoying rattle.

 

[mfdrookie516]

My tunze do that, which the manufacturer says is normal as the impeller is 'righting itself'. I'd imagine this is probably similar to the koralias.