just wondering what the advantages are of bio filtration.
There is no advantage
to using bio filtration, it is a necessity in the tank. If there were no bacterial populations in your tank, toxic ammonia would build up and make the tank uninhabitable whenever you added livestock. This is why we use some sort of bio-filter on every fish tank (fresh and salt) and ponds.
In your tank, your biofilter is currently the Emperor (assuming you use the biowheel), the substrate, and your liverock. Bacteria populate on any available surface area, processing nitrogen waste, and have been established soon after you started up your tank. These bacteria, and the "nitrogen cycle" they establish, are the basic life support system of your tank.
, whoever stated that you don't need to provide bio-filtration is misunderstanding the very basics of aquaria, at would be at the very least "concerned" over any other information provided. Unless
, they were stating that "you don't need to worry about it" because you already had established enough. It's tough to interpret what they were thinking.