If this is a reef tank then the bio balls do not add much to the system. Your live rock will do the job nicely. Also, when people say "Change your filter media often", many of them are saying daily. If your sump has an area between the drain line/skimmer area and the pump going back to the tank, then this area will act to trap waste, and will be easy to clean out, between and during water changes. I use a shop vac to do the water changes, sucks out the water, cleans the bottom, and is easy to dipose with litte mess. Oh yeah, I only use the shop vac for this purpose (important).