\i have used "Cycle" since day one and think it to be very good. Try to cycle the tank without live fish as it will harm them during the process however careful you are. If you start with a piece of fish (raw from your dinner maybe) it will generate the same chemicals as live ones.
after leaving it there for a day or two, Clean out your filter from the small tank with existing tank water just as you normally would, BUT put the water and the infusoria (Mucky green / brown stuff) in the NEW tank. Test water quality every day or two, When the readings are down and stable (depends on temp, climate , etc etc but could take a couple of weeks) you have a fully cycled SAFE tank for your fish.