Bio balls are only bad if you do not keep up with the maintenance on them. They would need to be cleaned every other day in order for them to not become nitrate factories. It's better to not use them IMO
. If this is for a saltwater setup, then I would suggest doing a simple DIY sump with a skimmer.
Wet/dry converted into sump with a Bubble Magus NAC7 cone skimmer, MAG7 return, 200 micron filter socks, Vortech MP40w + two returns for flow. Current Sundial T5 + two retro Icecap T5's (6 bulbs),