What kind of test kits are you using?
Right....zero last week; 80ppm this week? Does not sound correct.
Cycle your 180 with Stability and you can add fish now.
I 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 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/product_pages/Stability.html
Stability® will rapidly and safely establish the aquarium biofilter in freshwater and marine systems, thereby preventing the #1 cause of fish death: "new tank syndrome". Stability® 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 Stability® are non-sulfur fixing and will not produce toxic hydrogen sulfide. Stability® is completely harmless to all aquatic organisms as well as aquatic plants, thus there is no danger of over use. Stability® 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'sâ„¢ 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. Stability® does not contain any of the aforementioned bacteria.
The bacteria strains in Stability® 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), Stability® simply works harder and grows faster! The strains function in fresh or saltwater. Stability® contains both nitrifying and denitrifying bacteria, a blend found in no other product. Additionally, Stability® contains facultative bacterial strains which are able to adapt to either aerobic or anaerobic conditions. The bacteria in Stability® are non-sulfur fixing, another innovation in the industry. Most other bacterial supplements will form toxic hydrogen sulfide under the proper conditions. Stability® 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/article.cfm?aid=289&ref=4620&subref=AA&cmpid=E-_-CARE-_-32311-_-CYC
