Advice about sumps

[Cap'n]

I've often wondered about this claim. How is it that bioballs trap debris which leads to nitrate buildup while porous live rock does not?

Let's say, for example, you have a bunch of bioballs scattered throughout your rocks in the reef tank (nice picture, eh?). Would the balls be dirty clumps of nitrate crud beside a pristine, coralline covered live rock?

Seems to me it would come down to the microorganisms inhabiting the filter media. Which leads me to believe that they don't like plastic, if the bad bioballs claims are true.

Anybody have more details?