The reason I say to buy another Emperor is so that you don't have to buy cartridges for 2 different filters.
The amount of filtration needed to maintain an aquarium depends on a number of variables...among them aquarium size, individiual maintenance habits and fish population. Whatever your situation there are a few requirements basic to any setup:
Your filter of choice should provide all three types of filtration...Mechanical filtration -- a polyfiber filter pad or sleeve to screen out debris and dirt.
Chemical filtration -- activated carbon to adsorb pollutants.
NOTE: Many power filters will provide both mechanical and chemical filtration in a filter cartridge. Canister filters provide a filter pad or sleeve and a media container of some kind to which activated carbon can be added.
Biological filtration -- a dedicated biological filter that will support the growth of beneficial ammonia-neutralizing bacteria. Beneficial bacteria grow naturally on many surfaces within the aquarium. Because it is a wet/dry filter, Marineland's BIO-Wheel provides as much as 3000 times more bacteria-nourishing oxygen for superior effectiveness.
Your filter should generate a flow rate powerful enough to efficiently "move" the volume of water in your aquarium.
Filtration begins with flow rate. Filtration capacity and effectiveness are directly determined by the rate that water is pushed through the system combined with the quantity and quality of the filter media. The more water filtered totally (mechanically, chemically and biologically) in the least amount of time translates to cleaner water and healthier fish.
Clean, sparkling water is the mark of a healthy, thriving aquarium, and the key to maintaining optimum water quality in any aquarium is filtration.
Filtration media, in all its forms, is created for this purpose. Three types of filtration (each requiring different types of media) are necessary.
In mechanical filtration, a polyfiber filter pad or sleeve or micron cartridge screens out large particles of debris (like uneaten fish food) and solid waste.
In chemical filtration, a substance like activated carbon, clinoptilolite or ion exchange resins adsorbs (attracts and holds) pollutants which can cause discoloration, unpleasant odors and unhealthy conditions.
In biological filtration, a culture of beneficial bacteria eliminates toxic ammonia and nitrite by changing it to harmless nitrate. Beneficial bacteria will grow naturally on many surfaces inside the aquarium, e.g. gravel, decorative rock, plastic plants. Biological efficiency can be greatly increased by the use of a dedicated biological filter like BIO-Wheel or Bio Foam.
Fish health and aquarium success depend on the efficiency of these three types of filtration media.
Good Luck with your tank!!!