I have a Marineland Penguin 100 HOB filter for my 20G Long. I've been told it's not necessary to replace the filter every 3-4 weeks like it says on the package, and that it would be bad to change it frequently because the good bacteria grow on the filter. I read a review for a similar product - the Marineland Penguin Mini - and it says the BioWheel has the good bacteria on it. I'm fairly new to this, so can someone tell me what is the proper way to maintain a filter? How often do I change it? Am I supposed to be rinsing it in the water I change out every time I change water? What exactly does the BioWheel do, do I need to clean that? How often do I clean which parts of my filter? All tips are welcome! Thanks!