I was told that when you change a thermostat you should aslo change the impellar. should be a once a year thing. Is this true?? If it's pumping it should be fine?? don't wanna get caught in the water without water in the motor!!!
every couple years is fine in freshwater. If you haven't changed it yet or don't know its age, this would be the time to change it -- then you'll know how strong it pees with a brand new impeller.
