an example, ... an experience
a bucket of water, a bubbler, plant trimmings (from the aquarium) that have been dried & chopped/crushed.
one would expect with a large handful (after drying & crushing) this would give significant ammonia levels if left to break down in a bucket of water
-no lid, just a bubbler to keep water moving.
... not significant source of ammonia as i left this to wait a week before adding this water to the aquarium.
there's a world of different between theory of what could go wrong and actual experience of what happens
-where is your confusion ?
one of the biggest road blocks in aquariums i am finding is seeing a reliance on sterility (which i personally view as another word for death - something that nothing can survive with) and fear mongering.
for what i have come across, the aquarium hobby years ago relied on producing an aquarium far more akin to a self-sustaining tank then now, and now many people in the hobby would look at what was going on decades ago and argue till blue in the face "that can't be done, it's impossible", yet that's exactly what people did.
it seems many of our 'modern' innovations revolve around sterile aquariums and we're compensating by maintaining a system that is otherwise incapable of supporting itself, requiring scheduled maintenance from us to compensate for the parts of our mini contained ecosystem that we have removed.
there is a lack of fundamental basics on what is going on to keep our tanks healthy. and to make matters worse an established idea that we must keep the things out of the tank that are required to allow it to have a healthy balance.
so i'm not sure where your confused
is there more going on in my bucket of water, ... probably.
i'm got a ton of questions that to date, in or out of the hobby i am not finding answers to any of these questions.
often enough finding answers like "well these things sort themselves out, so you need not be bothered knowing about the details"
but as far as simple answers go
if tapwater has nigher than desired nitrites ...
putting the tap water in a bucket that is left to age and mature
allowing beneficial bacteria to culture and 'cycle'
this IS going to become safe for the tank relatively fast and no one needs to know the details behind it.
sometimes understanding what is going on gets in the way of just letting things do their stuff with a positive end-result
but i can see how this can lead to a breed of person that relies on a system where (s)he is told what they need to make it work and they lack any knowledge or background to understand anything differently
and so we have modern aquarium knowledge that looks at what was going on 100 years ago and there are those arguing till blue in the face "well that idea is just an impossible fantasy that cannot last" ... yet that's exactly what happened.