This is absolutely true for fish farming, or even a heavily stock fish tank. But a reef is less tolerant to the nitrate produced by these, where fish basically don't care (within reason).
They'll also do nothing (good) for any algae issues you might have.

"As a new reefer my take on it is that a small reef tank has significantly different requirements and often is "smaller" so less tolerance for waste buildup if your filter media gets gooey."

Right thats why I also dont use them in my reef tank either. Theoretically speaking if you could keep the crap out of the media with mechanical filtration I do not think it would be an issue but for the hobbyist its just not practical.

Palmer

Thanks very much for all the advices guys!!! Well those bio-balls are going in my garage now...lol

Manny