By "nitrate factory" I think they just mean that they house the beneficial bacteria that converts ammonia to nitrites and nitrites to nitrates, so yes, they technically are a nitrate factory, but that is what you want your biological filter to be doing for you. I hope this helped.
Understood - I just know while I had this tank setup as a Saltwater - the Saltwater enthusiasts frowned upon it for a multitude of reasons, was wondering what is different in the FW realm that it becomes more beneficial than harmful.
(Saltwater tends to rely on Natural filtration greatly, especially in smaller tanks, in which Live Rock and Water Flow become the "filtration" system).
Reposting questions so they do not get lost:
What determines if a Sump system should be used?
What determines if CO2 system is needed?
With 2 x 36W Power Compact lights in the Biocube (Replaced Actinic with Daylight so both are Daylight), am I fairly limited to certain plants? For example, should I avoid "Stems" or any other general plant type.
I have plenty of driftwood, the mechanical filter, 50/50 Flourite and Gravel, what kind of stock am I looking at?
Right now - I know I am getting a Roseline shark, but other than that no ideas yet. I really like the Knight Goby, but have not seen one at my LFS...