Tunze's rusting?

[double_g2k]

I'm reading on another site that Tunze impellers will rust out? Has anyone had any experience with this?
If it's true than is there any other pumps that aquire rust over time?

 

[ninjamini]

If there is any metal parts that are exposed I'm sure it will. salt water is corrosive. I would also think that rust is bad in a tank.