Matter of preference. But I think having the bio balls in the location indicated is slightly strange. Not sure how the water is not going stale in the skimmer section if the bio balls are point of entry for water from the main tank.
Unless water is being returned into the skimmer section, then the bioballs are fairly worthless for a few of the intended features they have.
If it was me, I would swap the bio balls and skimmer section if you like this design.
Again. it's preference.
75gal Salt, 18gal Sump, Skimmer, 60lb Live Rock, 90lb Live Sand, 3 Pwrhd, 2x55w Actinic, 2x55w 10k. Guest list: Goby Green Clown, Percula Clown and entire clean up crew.