I'll have to get a canister filter to replace the Emperor 400 that will provide sufficient bacteria for the tank.
An emporer 400 is a very good filter, not the best that money can buy, but quite competent. The biowheels provide a graet srface for bacteria, if you put regular filter floss in place of the cartridges, and/or put sponges in the secondary media containers, you will have great bio-filtration, just don't replace large quantities of media all at once (as was said) you will want to preserve the largest part of you media when you do maintenance. A 400 Emporer is great for this because of the dual media wells and dual bio-wheels, you can replace small sections of media very easily, and aloow the bacteria colony to grow an the new stuff while leaving estabilished bacteria in many other places in the filter.
Something else you can do is find a sponge and cut it to fit over the intake. this will add additional bio-and mechanical and help the media in your filter last longer. The one thing I don't see listed is tank size and bio-load, the concepts involved remain the same, but quantities of water waste etc. obviously have an effect on what you need. If you are running a 75 with 4 oscars on one emporer 400 and no substrate you will need another filter. If you are running a 46g with 4 tetra's no problem.
I have no experience with canisters myself, but from what I have been told they are great. I just wouldn't reccomend spending money on a canister if you already own an Emporer