If you can use a shop vac, they work really well.
If not, then 1/2 hose on both ends of a MaxiJet will suck up the brown crud, but will clog on solid pieces.
Every few water changes, I empty the water out of my sump down to 1/4 of as low as I can get it with the pump and then shop vac the rest out for a shiny clean sump.