Live Rock, Gravel and Light?
 

I am designing a sump in an old 50 gallon I have laying around. 33% of the sump will be a refugium that can be viewed through a window in the cabinet and 50% will be reserved for overflow in case of power loss. The refugium will be lit but not the reserve section. The reserve section will have a few inches of water in it and I am thinking of adding an inch of live sand or a few small live rocks to help filteration. My question is does live sand and or live rocks stay alive in the dark or with minimal light?

Thanks

Yes it does. It still maintains it's filtering and denitrifying properties and the bacteria continue to live in the rock. Probably the only thing you will be losing is any coralline that might be on the rock.

Thanks