I have a return pump (Mag 12) for my 100 gallon. Its been up and running now for 3 years. I have never cleaned it. I cleaned it between the 1st and 2nd year it was in use. However when I went from a 125 tank to the 100 now, I hard didnt think for the future and basically put all of the hard PVC
in and now there is no disconnect without cutting and splicing the PVC
...which is what I plan on doing soon.
However, when would you guys suggest I replace the Mag? Its 4 years old and running well. Still alot of push so do I wait until it goes out? Do I change it now?