I was interested in reading all this input in regards to Nutrafin Cycle, most of it is very wrong, so I will provide some accurate input to those that have asked questions in regards to this product.
Nitrifying products such as Nutrafin Cycle do contain live nitrifying aquatic bacteria that are in a dormant state. All such bacteria are really not active below 55deg. F, so dosing in cold water is of no use. Typical tropical temps are recommended for best performance. One of the advantages of using Nutrafin Cycle is the fact that it has been manufactured for over 20yrs., you are buying experience and the time it takes to refine a stabile effective product, many new entries that we find, although some of them are good product there is little time based research behind them to ensure the strains within are stabile over the long run and to apply all of the possible variables that can change, research on bacteria takes time as generations have to be evaluated in testing. Using dead organic matter or inorganic sources of ammonia as has been noted here is somewhat of a chance approach. If too much ammonia exists it can inhibit the development of the nitrifyers that convert nitrite to nitrate, not a good consequence of these methods, so dosing with ammonium chloride for example has to be done carefully and the dosage properly calculated as well as the dosage of a product like Cycle should it be used in conjunction. The fact that Cycle recommends re-dosing is simply related to the fact that the bacterial world is a predative one and one within which many other species can enter, via water changes, etc, etc...therefore to ensure predominance of the desired consortium it is recommended to re-dose to maintain and assure the bacterial flora is optimal, the comment about land based bacteria is totally incorrect. Make sure you shake the bottle well, you will see tons of particles which are actually bacteria and associate bio films. Remember Cycle took time to develop and what you buy in Nutrafin Cycle has many years of putting nitrifyers into dormancy and other situation that take generations to evaluate, its inexpensive insurance for your aquarium. So go ahead, set up your tank, add a reasonable load of fish, assure proper temp. and fitration and measure ammonia and nitrite regularly as you always should and keep feedings lean for the first few weeks.
If anyone else has questions about Cycle you are welcome to direct them to me, hope my lengthy post is read and glad to help.
