Don't torture your fish. Do fishless. It's not any quicker to do a cycle with fish so why do it?
That said, you cycle as long as it takes. Usually several weeks up to 6 weeks. There's a calculator that you can use to figure out how much ammonia to add to get up to the proper ppm
. You need an ammonia, nitrite, and nitrate test. You keep ammonia levels up to around 3-4 ppm
until you start seeing ammonia drop and nitrites raise. Continue adding ammonia to the tank up to your 3-4 ppm
level until nitrites start to fall and nitrates start raising. Do this until you can get 3-4 ppm
ammonia and nitrites to drop to zero within 24 hours. That means there's enough bacteria to take care of things. Do a large water change to reduce nitrates and add livestock.
You can quicken this process by adding material from an established tank. Filter media is a great thing to use. Wood, substrate, ect. Using water from an established tank won't really help as there isn't much bacteria in the water. It's mostly attached to things in the tank. But by seeding your new tank...it's just that much less time that you have to wait for the bacteria to develop naturally. Like Leestl said, in some cases...if you take a piece of filter media from a well established tank...you can have basically an instantly cycled tank. But you have to be careful to not add too much load too fast in this case because even though it's technically cycled...there's not a lot of bacteria. Add your livestock slowly. By doing a fishless cycle getting ammonia up to 3-4 ppm
, when it's all done you'll have such a huge amount of bacteria...that it can handle pretty much anything you can throw at it. You can do a full stocking all at once for a given tank size without causing a spike because there will be way more than enough bacteria to handle it. Over time...the bacteria will adjust to the load.