First of all, the Nitrogen cycle consists of this...
1. Ammonia is created from fish waste, fish respiration, decaying food/plants/dead fish.
2. Nirosomonas bacteria feed on the ammonia and produce nitrITES.
3. Nitrobacter bacteria feed on the nitrITES and produce nitrATES.
I did research a long time ago regarding Cycle and similar products. I had found out that these products do not contain typical nitrifying bacteria from what is found in a typical established tank (Nirosomonas and Nitrobacter). They don't easily multiply as quickly as the typical nitrifying bacteria in a tank, so they must be added artificially using these products.
I have heard about Bio-spira being more closely related to what is typically found in an aquarium and that allot of discus breeders swear by it. There is also allot of research information on Marinelands website on Bio-Spira here
. Unfortunately, I may have ADD, because I don't like reading so much information. LOL
Anyway, in regards to the above products, they may or may not work. Unfortunately, bacteria need to live and thrive. Therefore, they must survive in water, have a source of food, and oxygen. Unless the manufacturer can guarantee a "live bacteria" guarantee or maybe a direct packaging to home for the shipment of the products, they would be such a waste. Also, allot of these products sit on the store shelves for who knows how long.
When I first did the research, allot of these products did not have any experation dates, but from what I understand, they do now. Of course, I never bother, since I don't even look at them anymore.