Yes, use an external filter that will provide the material for the bacteria to live in.....
I then use
Seachem's Stability to provide the aerobic and anaerobic bacteria for my systems.
I use it in my QT anytime I wish to setup my QT for a fish(es) for QT purposes and never have any ammonia.
I recommend an external filter with sponges for the bacteria to setup.
I also used it in my 300g system when I started it up and never any ammonia.
I highly recommend its use for providing the necessary bacteria for a fully functional biological filtration system.
http://www.seachem.com/Products/prod...Stability.html
StabilityŽ will rapidly and safely establish the aquarium biofilter in freshwater and marine systems, thereby preventing the #1 cause of fish death: "new tank syndrome". StabilityŽ is formulated specifically for the aquarium and contains a synergistic blend of aerobic, anaerobic, and facultative bacteria which facilitate the breakdown of waste organics, ammonia, nitrite and nitrate. Unlike competing products, the bacteria employed by StabilityŽ are non-sulfur fixing and will not produce toxic hydrogen sulfide. StabilityŽ is completely harmless to all aquatic organisms as well as aquatic plants, thus there is no danger of over use. StabilityŽ is the culmination of nearly a decade of research and development and represents the current state of the art in natural biological management.
Sizes: 50 mL, 100 mL, 250 mL, 500 mL, 2 L, 4 L, 20 L
Why It's Different
Illustration of Stability's™ bacteria on biofiltration material. stability contains a synergistic blend of aerobic, anaerobic, and facultative bacteria
The bacteria used in competing products are inherently unstable. The conditions necessary for their growth and development fall into a very narrow range of temperatures, pH, organic loads, etc. When any of these parameters are not strictly within the proper range, the bacterial culture quickly crashes and dies. StabilityŽ does not contain any of the aforementioned bacteria.
The bacteria strains in StabilityŽ have been in development for over a decade. The necessary conditions for growth of our bacterial strains encompass a very broad range. When other bacteria begin to die off (usually from high organic loads caused by the undetected death of an organism), StabilityŽ simply works harder and grows faster! The strains function in fresh or saltwater. StabilityŽ contains both nitrifying and denitrifying bacteria, a blend found in no other product. Additionally, StabilityŽ contains facultative bacterial strains which are able to adapt to either aerobic or anaerobic conditions. The bacteria in StabilityŽ are non-sulfur fixing, another innovation in the industry. Most other bacterial supplements will form toxic hydrogen sulfide under the proper conditions. StabilityŽ will not, ever.
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If for some reason you don't or can't use Stability then here is another one:
http://www.liveaquaria.com/PIC/artic...-_-32311-_-CYC