As the mother of all Canister Filters your Fluval FX6 Filter Media Setup is very important. Understanding the flow of water in your canister filter is the first step. This way we can place the mechanical filtration first before the biological. The water in your canister should be at its cleanest before reaching your biological filtration. This will prevent detritus from clogging up the surface area of your biological filtration. The fluval fx6 filter media placement should always be Mechanical,