How clean do you keep your sump?

[Magickiwi]

I have a refugium in my sump so I don't empty it out for cleaning either. I do take a scrubber pad to the walls and bottom of the skimmer and return chambers every week or so but that's about it. I keep crabs in both chambers so all I'm scraping is diatom film, bacteria blooms etc. The refugium gets left alone.