The Nitrogen Cycle

Status
Not open for further replies.

backtotropical

Retired Mod
Retired Moderator ⚒️
Joined
Jul 9, 2007
Messages
4,481
Reaction score
4
The Nitrogen Cycle - A Beginner's Guide

‘The Nitrogen Cycle’ is the most important thing a fish keeper can learn about. It is an essential part of keeping fish alive and healthy in an aquarium.

What Is ‘The Nitrogen Cycle’?

‘The Nitrogen Cycle’ is a process in which bacteria convert toxic substances into less toxic substances. This is important in an aquarium as the toxic substances which fish produce naturally can quickly make them ill, or even kill them if not removed. Housing these bacteria is the main purpose of your aquarium filter.

How does it work?

Fish produce ammonia through respiration (breathing). Ammonia is also produced by fish food, fish waste, plant leaves and dead fish, if they are left to rot in the water.

Ammonia can be lethal to fish, even in very small quantities, so it is essential that it is somehow removed. There is no safe level of ammonia in an aquarium.

Ammonia is removed from the tank by the first of two types of friendly bacteria which live in your filter. The bacteria which remove the ammonia are called ‘Nitrosomonas’. They do this by converting ammonia into nitrite. Ammonia can also be used by live aquarium plants as food.

Nitrite is also lethal to fish, and so must be removed. There is no safe level of nitrite in an aquarium.

The nitrite is removed by the second of the two types of bacteria in your filter. This bacteria is called ‘Nitrospira’. They do this by converting nitrite to nitrate.

Nitrate is relatively harmless to most fish unless in large quantities. The nitrate level in the aquarium is controlled by performing frequent partial water changes. You can read about how to perform partial water changes in the link below. Live aquarium plants can also use nitrate as food.

Partial Water Changes

To help you understand ‘The Nitrogen Cycle’, below is a diagram which illustrates how the whole process works.

Nitrogen_Cycle_Diagram.jpg


I must note here (thanks Rabbut) that the bacteria i mention above are the bacteria responsible for 'The Nitrogen Cycle' in freshwater aquaria. Whilst the process is the same in saltwater, the bacteria which perform the function are different. I don't intend to cover saltwater nitrification here and this article relates to freshwater aquaria only.

How do I make ‘The Nitrogen Cycle’ happen in my aquarium?

You can see why ‘The Nitrogen Cycle’ is so important in an aquarium. It converts lethal ammonia into nitrite, and then to relatively harmless nitrate. Without ‘The Nitrogen Cycle’, our fish would quickly die of ammonia poisoning.

Unfortunately, when we buy aquarium filters, they do not come with Nitrosomonas and Nitrospira included. We must culture these bacteria in the filter in order to save our fish from the danger of ammonia and nitrite.

There are two main ways to culture these bacteria.


1. The first method is to add fish into the tank to produce ammonia. This will encourage the bacteria to start growing. This method is known as ‘Fish-In Cycling’ and you can read all about it in the link below.

Fish-In Cycling

The main problem with using fish for this purpose is that they are exposed to dangerous ammonia and nitrite during the period whilst the bacteria grow. This is probably the most common cause of death in aquarium fish.

2. The second method is to use an ammonia based solution to encourage the growth of the bacteria before the fish are added. This method is known as ‘Fishless Cycling’ and you can read all about it in the link below.

Fishless Cycling

The main benefit of ‘Fishless Cycling’ is that the bacteria are already in the filter when the fish are added, and so it eliminates the risk of ammonia or nitrite poisoning.
What if I don’t understand, or have some questions?

No problem. Feel free to start a new topic in the ‘New to the Hobby’ section of the forum, and someone will be glad to help you.

Happy Fishkeeping!!

BTT
good.gif


Please note: Unless otherwise stated, all text and images in this post are copyright Backtotropical, 2009-2012.
 
Status
Not open for further replies.

Most reactions

trending

Members online

Back
Top