Do you ever "clean" a sump?

I clean my sump, my pipes shouldn't have alage in them since algae doesn't grow without light but i'd clean the outside of them if needed.

In a freshwater setup, I'd check the bottom and make sure you've not getting a large collection of solid wastes building up in there. If you are, I'd vaccum that out at the same time as regular water changes are done--and add a pre-filter to capture it before it hit the sump!

Otherwise, periodic cleaning of the pipes and powerheads to prevent any algae and control the bio-film. Hard to say how often you'll need that--could be monthly, but more likely, once or twice a year will be suitable.