I found this an interesting article which backs up a few people on this forum, I myself have a bottle of cycle bought over a year ago that I don't know what to do with!! Sure it has been covered before but useful info nonetheless 
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Cycle*-Biological Aquarium Supplement
by Chris Cow, Ph.D. (Organic Chemistry)
*Editors Note: I believe the following information can be applied to many different brands of additives claiming to add nitrifying bacteria to the aquarium water and therefore eliminate or minimize ammonia and nitrite peaks in a newly setup tank. B.B.
Cycle is a product marketed by Hagen corporation and frequently pushed on newbies and experienced aquarists alike by the local fish stores. In theory, this product contains billions of the beneficial bacteria required by aquariums to aid in the cycle of a tank; that is, the conversion of ammonia into nitrite into nitrate. Hagen advocates the use of this product both while cycling a newly setup tank, and routinely during water changes. Hagen, the maker of Cycle, contends (if you read their website at http
/www.hagenpet.com) that it is the be-all and end-all of products: that it will cycle a tank, remove sludge, prevent disease, even act as a denitrifier (which, of course requires anaerobic conditions to occur...very unlikely to happen in the water column of your average aquarium). That, effectively, without it you condemn your fish to a hideous death. This is of course, nonsense, as is the idea that one should add it with every water change; if you have a healthy tank, your bacterial level remains essentially constant, and there is no need to add more (other than the need to put money in their pockets.) The big problem with Cycle, IMO, is that there is no independent research to support its use whatsoever. The "research" presented on the Hagen website consists solely of a graph which shows how the addition of Cycle reduces ammonia and nitrite peaks in a newly setup tank. There is no mention of statistical relevance (does their data come from one experiment, or one hundred?), or of any efforts to control other factors. Many factors will control the length of time and the severity of the spike associated with an aquarium cycling; these include, but are not limited to the temperature, bioload, filter type, light, etc. It would take a very large number of experiments to be able to rule out most of these other factors from influencing the experiment. Plus, the only evidence supporting their claims comes from their own in-house chemists; I prefer more impartial, independent studies. As an aside, I also don't really believe doctors who work for the tobacco companies when they tell me that nicotine is neither harmful nor addictive.
Recently, Dr. Tim Hovanec has published a number of very interesting articles in peer-reviewed publications which indicate that Nitrobacter bacteria is NOT responsible for oxidizing ammonia to nitrite in home aquaria. Instead, his results indicate that it is a Nitrospira sp. More recent work has shown that the assumption that Nitrosomas bacteria are responsible for the oxidation of ammonia to nitrite may also be incorrect. A review of his scientific papers with references are in AFM magazine:
http/www.aquariumfrontiers.com/1998/mar/...nce/default.asp
http/www.aquariumfrontiers.com/1998/june...nce/default.asp
http/www.aquariumfrontiers.com/1998/aug/...nce/default.asp
If his research is correct, and it has certainly not been disproven (or confirmed) to my knowledge yet, then the bacteria in Cycle are in fact the wrong bacteria for the job. His research has also confirmed that the bacterial supplements containing Nitrosomas and Nitrobacter bacteria have little or no effect on a cycling tank compared to control tanks. Others have shown that, contrary to Hagen's claims, only about 6% of the bacteria in a new bottle of Cycle is biologically active... this number will decrease drastically with an extended shelf life. Enquiries about this study to Hagen, and requests for additional information were made by a fellow aquarist; Hagen's results were very insulting, ridiculing Dr. Hovanec's work, using vulgar language, and effectively stating that more evidence wasn't necessary, because any fool could plainly see that Cycle works. Needless to say, this response did little to increase my confidence in their product or their scientific method. Many aquarists that I've spoken with have stated that empirically (and I've observed when using this on my own tanks), Cycle has had either a zero or a minimal effect on their cycling process. I do not understand spending large amounts of money (around $16 / 500 mL bottle here) for a product which has little or no effect. I believe that Hagen, as the maker's of Cycle, are already suspect as they advocate their product's repeated use with every water change, even though a basic knowledge of the nitrogen cycle would indicate that this usage is totally unnecessary. IMO, you are much better off spending that money on more fish, a larger tank or a better filter system.
jump
Cycle*-Biological Aquarium Supplement
by Chris Cow, Ph.D. (Organic Chemistry)
*Editors Note: I believe the following information can be applied to many different brands of additives claiming to add nitrifying bacteria to the aquarium water and therefore eliminate or minimize ammonia and nitrite peaks in a newly setup tank. B.B.
Cycle is a product marketed by Hagen corporation and frequently pushed on newbies and experienced aquarists alike by the local fish stores. In theory, this product contains billions of the beneficial bacteria required by aquariums to aid in the cycle of a tank; that is, the conversion of ammonia into nitrite into nitrate. Hagen advocates the use of this product both while cycling a newly setup tank, and routinely during water changes. Hagen, the maker of Cycle, contends (if you read their website at http
/www.hagenpet.com) that it is the be-all and end-all of products: that it will cycle a tank, remove sludge, prevent disease, even act as a denitrifier (which, of course requires anaerobic conditions to occur...very unlikely to happen in the water column of your average aquarium). That, effectively, without it you condemn your fish to a hideous death. This is of course, nonsense, as is the idea that one should add it with every water change; if you have a healthy tank, your bacterial level remains essentially constant, and there is no need to add more (other than the need to put money in their pockets.) The big problem with Cycle, IMO, is that there is no independent research to support its use whatsoever. The "research" presented on the Hagen website consists solely of a graph which shows how the addition of Cycle reduces ammonia and nitrite peaks in a newly setup tank. There is no mention of statistical relevance (does their data come from one experiment, or one hundred?), or of any efforts to control other factors. Many factors will control the length of time and the severity of the spike associated with an aquarium cycling; these include, but are not limited to the temperature, bioload, filter type, light, etc. It would take a very large number of experiments to be able to rule out most of these other factors from influencing the experiment. Plus, the only evidence supporting their claims comes from their own in-house chemists; I prefer more impartial, independent studies. As an aside, I also don't really believe doctors who work for the tobacco companies when they tell me that nicotine is neither harmful nor addictive.Recently, Dr. Tim Hovanec has published a number of very interesting articles in peer-reviewed publications which indicate that Nitrobacter bacteria is NOT responsible for oxidizing ammonia to nitrite in home aquaria. Instead, his results indicate that it is a Nitrospira sp. More recent work has shown that the assumption that Nitrosomas bacteria are responsible for the oxidation of ammonia to nitrite may also be incorrect. A review of his scientific papers with references are in AFM magazine:
http
/www.aquariumfrontiers.com/1998/mar/...nce/default.asphttp
/www.aquariumfrontiers.com/1998/june...nce/default.asphttp
/www.aquariumfrontiers.com/1998/aug/...nce/default.aspIf his research is correct, and it has certainly not been disproven (or confirmed) to my knowledge yet, then the bacteria in Cycle are in fact the wrong bacteria for the job. His research has also confirmed that the bacterial supplements containing Nitrosomas and Nitrobacter bacteria have little or no effect on a cycling tank compared to control tanks. Others have shown that, contrary to Hagen's claims, only about 6% of the bacteria in a new bottle of Cycle is biologically active... this number will decrease drastically with an extended shelf life. Enquiries about this study to Hagen, and requests for additional information were made by a fellow aquarist; Hagen's results were very insulting, ridiculing Dr. Hovanec's work, using vulgar language, and effectively stating that more evidence wasn't necessary, because any fool could plainly see that Cycle works. Needless to say, this response did little to increase my confidence in their product or their scientific method. Many aquarists that I've spoken with have stated that empirically (and I've observed when using this on my own tanks), Cycle has had either a zero or a minimal effect on their cycling process. I do not understand spending large amounts of money (around $16 / 500 mL bottle here) for a product which has little or no effect. I believe that Hagen, as the maker's of Cycle, are already suspect as they advocate their product's repeated use with every water change, even though a basic knowledge of the nitrogen cycle would indicate that this usage is totally unnecessary. IMO, you are much better off spending that money on more fish, a larger tank or a better filter system.
I guess we will have to make do without Bio-spera here in th UK for a bit then! 
