I can't believe some of what I'm reading here. Normally the cycle process or "Nitrogen Cycle" will take 3-6 weeks when using fish, a fishless cycle can take much longer due to the lack of waste being produced to feed the growing bacteria. If you choose to use fish to cycle you should use hardy fish such as zebra/giant danios, minnows, and larger barbs, my preference being danios. The fish and excess food that may not get eaten will produce waste (Ammonia) which feeds a naturally occurring bacteria called Nitrite, which is harmful to fish and more often then not kills them. It takes about 1-2 weeks for Nitrite to form when Ammonia is present. To simplify it Nitrite basically "eats" Ammonia, which is why your reading starts to disappear when you start to develop Nitrite. About a week or so after you develop NitrIte, you will get NitrAte (also known as beneficial bacteria) which, again, essentially eats the Nitrite. Once this process is complete you should have no Ammonia, no Nitrite and you will have Nitrate. To simplify it now, fish create waste which makes Ammonia, Nitrite develops and removes Ammonia, Nitrate develops and removes Nitrite, end cycle. You need to do water changes to keep Nitrates at lower levels because at very high levels over time they can also cause damage to fish but when maintained at safe levels, <40ppm, ideally <20ppm, you have nothing to worry about. There are products that claim they can instantly cycle aquariums but these are blatant lies. Most of these products help to cultivate Nitrate because they are NitrIte in a bottle, not the finished product, they can accelerate the cycle process but it is in no way shape or form instant. Any LFS that says they use it in tanks may be telling the truth but they aren't instantly cycling tanks every time they put discus in them, it's adding bacteria (Nitrite) to feed the beneficial bacteria (NitrAte). They essentially increase the good bacteria colonies by adding these products and if any LFS, Petsmart, etc ever tells you it's instant they're lying. If there was an instant cycle product on the market don't you think every fish keeper and his brother would be using it? I think it would be much bigger news if such a product came onto the market. My guess as to why there is no Nitrate in a bottle is that the bacteria cannot live extended periods in a bottle with no food source (fish waste). Take my word, I've worked in fish stores until very recently and know a lot about many products that usually doesn't get to the customer because of shady sales people. These products need to be properly explained to each and every customer because if they aren't they go out and tell their friends and fellow forum members about them and misinformation becomes a huge issue. At the end of the day everyone is hurt by it, those who loose their fish, those who cause others to loose their fish, and LFS's who have to deal with angry customers who won't ever want to come back.