Had a marine setup for around 6 months now. 240L + 30L sump, skimmer, 40kgs live rock, small clean up crew (5 mexican trubo snails, 3 hermits, 1 shrimp), few fish.
I seem to get a lot of detritus/debris on top of the sand that just sits there. Looks like bits of algae, or broken bits etc etc...