The problem with Bio-Balls is that the offer a paradoxical issue of husbandry. First off, Bio-Balls need to have water trickled over them so that they receive a mix of water and air exposure. Secondly, they must be cleaned so that they don't release too many nitrates to the water, but at the same time are not suppose to be disturbed. I could write volumes. Anyway, Bio Balls don't work very well, nor do Bio wheels. Also, I believe that Biowheels and bio balls are prone to depleting your system of CO2.