Good - Single Canister - You can run GFO
. While not ideal, it's also possible to run both in a single canister by placing the GFO
in the bottom and GAC
on the top (catches GFO
fines) separated by sponges. The downside is GAC
typically last much longer than GFO
. When used in a single canister, you're forced to change out both at the same time.
Better - Dual Canister - Allows both media to be run in their own canisters and changed out individually.
Best - Two individual Canisters - Same benefits as dual, but adds the ability to control the flow rates individually (you want GFO
to tumble, whereas the GAC
should have lower flow for longer contact time and to prevent tumbling and the creation of fines.)
fines is important as studies suggest carbon fines contribute to Head and Lateral Line Erosion (HLLE) - also referred to as Lateral Line Disease (LLD.)