I'll admit, I received a lot advice on this forum and others that had warned me against using Cycle. Not that is was harmful to the tank per-se, but did more or less nothing other than rob your wallet.
I happened to have received Cycle from a friend late into the establishment of my tank. I was struggling with the natural cycle, and was told that time would be the solution.
Since the product was free to me, and everything else wasn't producing any results, I went ahead and used the appropriate amount of 'Cycle' as recommended by the directions.
Within a few days, my tank did indeed improve. HOWEVER, it may have had NOTHING to do with 'Cycle'...my tank could have just been taking its time on its own and would have produced these reults anyway. It could be just a coincidence, so I am not reporting favor towards 'Cycle'. What I am saying is I did use it weeks into a fishy cycle, it was free, things started to turn around within a few days of use.
But it appears the jury is still out on it. I'd personally liek to use Bio-Spira, but NOBODY has it right now. At least I can't find anybody.