This is a discussion on just scored this within the Saltwater Aquariums forums, part of the Saltwater Fish and Coral Reef Tanks category; -->
iv heard that some people replace bioballs with live rock rubble...has anyone tried this?...
I guess the Reef Plugs are the same in a way, though man made, the place I get them from have a load of tanks with Live Rock in them and the bags of Reef balls/Plugs(100 per bag) all sitting in amongst the Live Rock for a few months before they sell them.
I don't have a light over my sump like Live Rock sumps though.