Sump Questions

[Coralgurl]

I'm still getting used to this sump set up and have been tweaking things as I go. I have set up a refugium and finally got a light installed last night. When I turned it on, I was surprised by the amount of crap/crud in the sump. Does anyone purposely throw a CUC in to keep it clean? If so, what's good to go in? I know bad crabs will get banished etc. I try to clean out as much as I can with water changes, but with adding more equipment, its getting a wee bit tight. Or, is this nothing to worry about?

As far as equipment in the sump, I have a RO Skimmer, BRS reactor running carbon and gfo and a filter sock on my overflow (just 1).

Thanks