Originally Posted by nsu7
So, I just can't understand how they're bad nitrate factores.
They're actually not. Much like bioballs, it's lack of proximity to denitrifying bacteria. Strict anaerobes are but one, preferabley facultative but the closer the aerobic bacteria is to the facultative/anaerobic the more efficient the process. The further the they are apart, the longer less efficient the process becomes. Biowheels and the like do exactly what they're supposed to ( nothing more) and quite efficiently. FWIW
, all types of bacteria (aerobic/anaerobic/factultative) grow within the visible area's of the tank, it's just that the denitrifying type cannot grow in sufficient numbers to do any good without "safe harbour" if you will spaces in their favor. ie sandbeds and LR