I have used bio balls for a breakwater before when I had a small sump and the bubbles were bad. However it was only about 10 or 15 of them. I had a full box so I rotated clean ones through every week and bleached the others to keep them clean and free of gunk.
As far as I know, that goes for any filter floss-type media, including sponges. They'll accumulate bacteria and become a nitrate farm, so keep them clean or, better yet, have spares to rotate through while you clean the old ones.