Sorry to be long winded with what foollows. But, the more one knows in this hobby the better you get in both choosing and caring for your fish and the less stressful it becomes for you.
If you seed bacteria into new tank, depending on how you do it, you can do anything from making it fully cycled in a day or two to just giving it some level of push.
However, there is one big difference between doing the more traditional fishless cycle with neither live plants nor seeding seeding bacteria and doing it wile either or both of these things.
The traditional method starts with almost nothing that uses ammonia present. When the ammonia is added the few bacteria that have come in with out tap water and out of the air will respond by reproducing which they do relatively slowly. This means if you need them in huge numbers it will take some time for them to reach a level where you see the ammonia going down and the nitrite coming up. The same thing will apply to the nitrite and nitrate.
Now, what happens when plants and or seeded bacteria are used? The answer has to do with how they work. Plants thrive on ammonia in the form of ammonium (NH4). Most of the ammonia in our tanks is in this form. The bacteria want the ammonia (NH3). But there is a big difference in what happens when wither consume what they want.
1. Plants consume NH4 faster than bacteria consume NH3,
2. Bacteria will make Nitrite and Nitrate as a result of consuming NH3.
3. Plants will not make an Nitrite and will actually use Nitrate if there is not enough ammonium.
Next, when we use a viable bottle of live nitrifying bacteria of the proper types, what we have is both those that process ammonia and those that process Nitrite. More importantly these should be balanced so that the amount of Nitrite the ammonia ones can convert to Nitrite, the Nitrite ones present can convert to Nitrate.
For any fishless cycle where there are not ways to handle all the ammonia and Nitrite, time and more ammonia will have to be added to complete the cycle.
The biggest wild card in this is when we have live plants in a new tank. Most of our tank plants want to use the ammonium in the water (a very few prefer Nitrate). But, when it comes to the various species and varieties of plant we might choose combined with a variable level of the one might decide to have, it becomes impossible to create a step by step guide that works for anywhere near eve a lot of the possibilities. But, for those who know what they are doing one can plant a tank sufficiently to allow them to stock to some extent as soon as the plants are established.
What also happens when one adds live plants, they are also adding some amount of the very bacteria we need, They actually live on the plants. It is not possible the have a tank 100% cycled from just what the plants do because there will always be some amount of the bacteria. on the other hand one can have a tank with 0 live plants which is close to completely cycled because of the bacteria there. I say close to because if one has algae, one has something else using some of the ammonia.
So, if one is doing a fishless cycle and is using either/or seeded bacteria/live plants, the only way to know where things stand is to dose ammonia, wait and test. The problem with this is that some plants are sensitive to elevated ammonia. So the way to avoid this if you do not know if any of the plants you have might be this way is to reduce how many ppm of ammonia you add. In the fishless cycling article here that is normally 3 ppm.
With plants I suggest one should use 1 or 2 ppm max. The goal is to turn it all to only Nitrate in 24 hours or fewer. With enough plants Nitrate could be 0 to match those reading for ammonia. You can also decide to star with 1 ppm and if you get all )s the next day to repeat things but use 2 ppm. If you are in a rush for fish then if the tank handle only 1 ppm you cannot add as many fish as you would had it handled 2 ppm.
However, you will still need to stock in stages when you know you will be relying on plants for handling a part of the cycling chores. However, one of the big benefits of traditional fishless cycle is that it allows one to stock the tank fully all at once. Doing this means one doesn't have to think about quarantining new fish as the tank is that already as it is devoid of fish until we add them. The more one can add at once, the better in most cases. But there are fish which need a more mature tank before they are added.
