Still on Water Changes

Before I write further on water changes, let me tackle some basic concepts of the nitrogen cycle as I get quite a few inquiries on the topic. So let me try to simplify it in a way that it can be applied by the hobbyist in dealing with a new aquarium and/or maintaining an old one as I believe information that is known will only serve its purpose if it is applied and again, silly as it may sound, I do not see this in most discussions and even reading materials.

The operative word to begin with is 'recycle.' It is a process of moving one particular form of element - nitrogen which is part of ammonia, nitrite, nitrate - to another form so that other organisms could use it (like ammonia, nitrites, nitrate) to the final end-product (surprise, surprise - back to nitrogen) so that it can be reused, thus the terms I use is 'recycle.' That is nature at work, nothing is wasted as nitrogen is part of the basic elements of life (specifically of proteins - building blocks of life) and as such is needed by any living organism.

One organism takes in proteins and excrete it in another form. But as per nature's design, nothing is wasted thus the waste produced by one is actually 'food' for another, whose own excreta will also be consumed or utilized by another until nitrogen is released back in nature from which plants take it up and start the process again. Recycling indeed was never new, it has been there all along.

Now, fish excretes what it eats. What it excretes remains within a closed system (that is what an aquarium is until you do water change). The waste then is decomposed by another set of organisms that produces ammonia and this is where all the problems start. Ammonia. One more fine detail and quite important too, fish do excrete ammonia, most of them through their gill membranes - so one needs no poop to have ammonia in your aquarium because the gill membranes releases most of it. Thus when one encounters high ammonia levels, fish gill membranes are the first to be affected. Gas exchange is impaired and that could really make it dangerous for the fish.