I have a 120 gallon cichlid tank which is fully established and running fine. Was wanting to add a 2nd canister filter on it for additional filtration. My question was whether or not I need to do anythign special when adding this 2nd filter. I know people talk about seeding a filter. Does this apply with adding a 2nd filter? Just don't want to cause any shock to my fish. Any help would be great. Thanks!