I also have a lot of live rock in the display tank as well.  I was just wondering what else to put in my sump to help the over all health.   

Those little balls are probably bioballs.  They are fine but there are newer products that do a similar function.  The whole idea is that they increase surface area to allow for more colonization by beneficial bacteria to aid in your biological filtration.  If you decide to use them, just make sure they get a little flow through them because you don't want them to cause a dead zone deep within which can cause an anoxic area that traps waste and could potentially cause problems.  If they have some flow, this shouldn't happen.

Some other ideas you could use as well/instead:

1 - live rock.   There's really no substitute for live rock, in my opinion.  Creates tons of surface area for your beneficial bacteria, looks good, and provides structure within the tank

2 - bioblock (https://www.saltwateraquarium.com/xport-bio-plate-9-x-8-x-1-50-brightwell-aquatics/ ) . I use one of these in my refugium.  It does the same thing as the bioballs in a more compact area by providing massive surface area for beneficial bacteria.

3 - biopellets (https://www.saltwateraquarium.com/np-active-pearls-450-ml-dr-tims/ ) I use these in a reactor before my skimmer.  They do provide a small amount of surface area but area mostly for providing a carbon source (similar to vodka, vinegar, etc) for those bacteria to flourish

Anyway people have great tanks using bioballs, so they are fine to use to grow beneficial bacteria, but I think there are newer products that do the same thing in a smaller package, that's all!

Thanks for the replys