Is there any difference in using bioballs as opposed to live rock in a sump.
I was told that the bioballs will function the same as live rock as long as the balls stay summersed under water at all times.
Bioballs don't have the ability to convert nitrates to nitrogen gas resulting in ever increasing nitrate levels. Of course, that's not taking water changes into account.
I agree with Deanos but I'd like to add that if you are using live rock rubble, they won't be able to convert nitrates to nitrogen either. Live rock rubble are simply too small therefore having too much surface area exposed to oxygen for anaerobic bacteria to grow in. If you are using really dense rock then this won't be a problem.
To answer your question though, bioballs will accumulate with detritus.