Nitrogen Cycle

[Neil]

I am just learning about this nitrogen cycle.   Very interesting.   Lets say you set up a new aquarium and added some plants (no fish yet).

Would ammonia build up in that tank and start the cycle?  Or is the only way to get ammonia in the tank (to start the cycle) is to

add fish?  So, I am asking if you just put some gravel and plants in an aquarium with a filter and heater would ammonia ever be present or would you never have ammonia in the tank?

[FrozenFins]

I would say most people start the cycle with no fish. The nitrogen cycle starts naturally. You can always speed up the cycle by adding a source of amonia such as: -A very small bioload of fish, -fish food, -fish poop. I have done the fish food and fish poop method and both got my tank cycled in a little over a week. If you decide to let nature take its course and not speed up the nitrogen cycle, the average cycle will take 4-6 weeks (of course every aquarium is different)

If you would like to learn more about the nitrogen cycle there are PLEANTY of threads for this. Simply search it up in the search bar.

Also here is a playlist of cycling videos @Irene did on her experiments on the cycle:

 

[Cory]

From working in a fish store. Over 90% of people we interacted with didn't start with ammonia. It's actually not my preferred method as well. I much prefer plants.

 

Here is the video I did on cycling a tank with plants.

 

[darkG]

TLDR: A source of nitrogen is needed to grow the microbial army of ammonia-eaters.

I think people mean something like this when they say "cycled": the aquarium can handle the ammonia that livestock will bring into the equation. Most often this capacity depends on certain bacteria and archaea in sufficient numbers. To grow to capacity, they need to feed. Plants + inert substrate (sand or gravel) doesn't offer much. It is my understanding, therefore, that sand and plants will hardly enable a significant ammonia-processing microorganism community, depending on dead leaves and flies falling into the tank more or less. The tank will never be cycled in the meaning suggested above. (Often people may add some form of plant food though).

Now plants do for sure process ammonia too. Separate from the microbial gang, competing with it actually. (But also helping it by providing leaf real estate and oxygen). So I think a tank with established fast growing plants is possibly ready for fish. Independent from the microbial nitrogen cycling.

In reality things are generally a bit more fuzzy, few things in nature are truly separate from other... things. 

caveat: I have basically no experience whatsoever.