Lecture 2 - The Nitrogen Cycle

The Nitrogen Cycle and Cycling your Tank

You can call it cycling, biological cycle, startup cycle, break-in cycle, or the nitrogen cycle. it does not matter what you call it, every newly set up aquarium goes through a process of establishing beneficial bacterial colonies. Older aquariums also go through periods during which the bacterial colonies fluctuate.

Failure to understand this process, and how to measure and control it, is the largest contributing factor to the loss of fish. Learning what it is, and how to deal with critical periods during the nitrogen cycle, will greatly increase your chances of successful fish keeping.

The Waste Problem
Unlike nature, an aquarium is a closed environment. All the wastes excreted from the fish, uneaten food, and decaying plants stay inside the tank. If you do not eliminate all of this waste, your beautiful aquarium would turn into a sewerage pond in no time at all.

Actually, for a short period of time, a new aquarium does become a toxic waste pond. The water may look clear, but don't be fooled. It's loaded with toxins. Fortunately bacteria that are capable of converting wastes to safer by-products begin growing in the tank as soon as fish are added. Unfortunately there aren't enough bacteria to eliminate all the toxins immediately, so for a period of several weeks to a month or more, your fish are at risk.

However, you need not lose them. Armed with an understanding of how the nitrogen cycle works and knowing the proper steps to take, you can sail through the break-in cycle with very few problems.

Stages of the Nitrogen Cycle

There are three stages of the nitrogen cycle, each of which presents different challenges.

First Stage :
The cycle begins when fish are introduced to the aquarium. Their faeces, urine, as well as any uneaten food, are quickly broken down into AMMONIA. Ammonia (NH3), is highly toxic to fish. Any amount of Ammonia (NH3) is dangerous, however once the levels reach 2 ppm, the fish are in grave danger. Ammonia usually begins rising by the third day after introducing fish.

Second stage:
During this stage Nitrosomonas bacteria oxidize the ammonia, thus eliminating it. However, the by-product of ammonia oxidation is NITRITE, which is also highly toxic to fish. Nitrites levels as low as low as 1 mg/l can be lethal to some fish. Nitrite usually begins rising by the end of the first week after introducing fish.

Third stage:
In the last stage of the cycle, Nitrobacter bacteria convert the nitrites into NITRATES. Nitrates are not highly toxic to fish in low to moderate levels. Routine partial water changes will keep the nitrate levels within the safe range. Established tanks should be tested for nitrates every month to ensure that levels are not becoming extremely high.

The tank will go through these three stages about three times during the first 4-6 weeks of fish being added to your tank. REMEMBER if your tank has cycled with 6 fish, and you suddenly add another 12 fish into the tank the cycle will basically start all over again, as the bacteria levels need to catch up with the new "Bio Load". This is one reason for people having fish loss after adding new fish. Do it slowly and your problems are minimised.

I will expand on this this on my next post

 

Thanks, very interesting reading. Do appreciate you taking the time doing the lecture series. It will be very helpful to us newbies

 

Thanx and it is a pleasure

 

Looking forward to the next post!

 

The Nitrogen Cycle Part Two - Tips, Hints and Info

The Nitrogen Cycle Part Two - Tips, Hints and Info

When your cycle begins and the ammonia starts building up there can be two types of ammonia - either ionized or unionized ammonia. The ionized form, Ammonium (NH4), is present if the pH is below 7, and is not toxic to fish. The unionized form, Ammonia (NH3), is is present if the pH is 7 or above, and is highly toxic to fish. Any amount of unionized Ammonia (NH3) is dangerous. So keeping tabs on your pH is a good idea during the cycling process. DO NOT try to correct the pH below 7 to try and avoid the cycle, this will mean many dead fish.

One thing we all experience when cycling a tank is an algae bloom or growth, One way to combat the algae problem during cycling is to buy several (cheap) bunches of plants and put them in the tank. No need to plant them, just throw them in. You probably won't need or want them anymore after your landscaping plants and the aquarium establishes itself. This "out-competes" the algae and your "Planted Tank" will be virtually free of this pesky algae.

When cleaning your tank and filter, NEVER rinse your filter media with regular tap water , the chlorine in the tap water will kill your benificial bacteria instantly and you will have to start all over, rather rinse your filter media in tank water.

Another common problem is people "over clean" their tanks during partial water changes and maintenance. Remember - never clean more than half your filter media at any one time.

NEVER take everything out of the tank, clean it in tap water, wash your sand and rocks and then put it all back together.... What you have just done is start a new tank and it will have to cycle all over again.

Finally Plants help all these processes so the more plants the better - BUT remember you still need to see your fish !!!!!!!!!

Please feel free to add any tips or hints you know..

 

Maybe you can add acceptable levels (in your opinion) to this paragraph, before people think that they should be making it zero, which is damn near impossible for any extended period of time.

Well you need some form of filtration, a sump is probably better due to it adding more water volume to the tank essentially, but ultimately any decent filtration should do the job.

The bacteria is what breaks it all down, and you have that in almost any filtration system, not just a sump.

 

Please forgive my ignorance here, I am VERY novice... but what on earth is a sump?

(I "inherited" a tank, so the answer is: No, I didn't do any research before I got into this hobby)

 

Madam - A sump is a large filter which normally sits below your tank and is normally a smaller tank..

Butcher - Adding a sump or any other type of filter will help with Nitrates, Your sponge filter also helps with nitrates

Sauron - Agreed, just try to keep Nitrates as low as possible.

THERE IS NEVER ENOUGH FILTRATION

 

Oh, I've seen those. ) Now I know, thanks!

 

Sponge filters are as good as any other filter - In fact in breeding situations I do not think you can beat them. The problem is that because they are an old and SIMPLE method a lot of people think they are not as effective in the entire Nitrogen cycle.

However there have been tests done, such as HOB vs Sponge and the sponges have won.
Just remember there are sponge filters - and then there are sponge filters....

I think when I have finished the SUMP lecture I will do a SPONGE lecture.

AGAIN .......

There is NEVER enough Filtration..

 

[FONT=Arial, Helvetica, Avant Garde]Hi Butcher - Nitrobacter as a group are not only anaerobic, there is also aerobic breakdown into Nitrates - see below taken from American Aquarium - [/FONT][FONT=Arial, Helvetica, Avant Garde]Carl Strohmeyer - 23/06/09[/FONT]
[FONT=Arial, Helvetica, Avant Garde]
When an organism dies, nitrogen is moved from plant or animal into the inorganic chemical ammonia by the process of bacterial decay. Ammonia is also produced by bacteria in the breakdown of protein. This process is called Mineralization and is the end result of the metabolism of food. However, ammonia is produced from both metabolism and mineralization. The decomposition (mineralization) process produces large quantities of ammonia (NH3) through the process of ammoniafication. Heterotrophic microbes (organisms that require organic substrates to get its carbon for their growth and development) utilize the organic compounds of decomposing matter as their carbon source. Ammonia (NH3) is the byproduct of this consumption.
Ammonia, in its neutral state, exists as ammonium (NH4+). Ammonium (NH4) is formed by the protonation (the addition of a Proton (H+) to the molecule. During this process of protonation NH3 (which is a base) converts into a weak acid (an acid which has the tendency to lose, or "donate" a hydrogen ion, also known as a “Brønsted-Lowry acid”. This tendency to “donate” a hydrogen ion is how NH4 converts back to NH3 as pH rises.

Ammonia is assimilated in more than one way. Plants (such as Hornwort) and algae can assimilate ammonia and ammonium directly for the biosynthesis. The remaining bulk of decomposed byproducts are utilized by bacteria in a process called nitrification. Ammonia does not last long in a healthy aquarium environment, fortunately. Nitrifying bacteria such as Nitrosomonas quickly break down ammonia into less toxic Nitrite (NO2). During this process, specific species of nitrifying bacteria strip the ammonium of its hydrogen molecules as an energy source. Oxygen molecules are then affixed to the stripped nitrogen, forming the oxide nitrite (NO2).
Another group of bacteria (Nitrobacter ) utilize the enzyme nitrite oxidase that is then responsible for converting nitrite into nitrate (NO3). This nitrate can either be used by plants as a nutrient source, or can be further broken down into nitrogen gas (N2) through the activity of anaerobic bacteria such as Pseudomonas . It should be noted, that without oxygen (nitrification is an oxidative process), none of this process can take place.

[/FONT][FONT=Arial, Helvetica, Avant Garde]True nitrifying (Autotrophic) bacteria are considered to be those belonging to the family Nitrobacteraceae whose energy sources are derived from the chemical conversion of ammonia to nitrite, or, nitrite to nitrate (Autotrophic bacteria are organisms that produce complex organic compounds from simple inorganic molecules). They require oxygen, utilize mostly inorganic (without carbon) compounds as their energy source, and require carbon dioxide (CO2) for their source of carbon. In the case of the Nitrobacteraceae these energy sources are derived from the chemical conversion of ammonia to nitrite, or, nitrite to nitrate. The desired Autotrophic aerobic bacteria of nitrifying bacteria are present everywhere (e.g., in the air), oxygen and at least some moisture is present (not in areas void of oxygen) (reference: 3). It is important to note that although the desired nitrifying species of bacteria are “all around us”, they do not readily store in sealed oxygen free containers (dying rapidly without oxygen), and it takes some time for the sparse air born nitrifying bacteria to populate an aquarium or pond, so do not expect these bacteria to “magically” populate your aquarium overnight, even a re-started aquarium will need to be re-populated (please see cycling methods further down in the article).[/FONT]

 

Wow, Zafgak, you know your stuff :smile1:
I'm looking forward to the session on Sponge filters,since that's what I've got. Might have some questions too.

Really interesting, thanks for starting these lectures up.

 

Thanx for the compliment - but I cannot take credit - most of this knowledge is available in books and/or the net, I just read a lot ....

 

Hi Butcher - do a google on coil de-nitrators - may answer a few questions

Bear in mind that to set up an effective anaerobic de-nitration process is a LONG process.. if you have any specific questions give me a PM.

I think a more detailed lecture on Nitrates may be an option but TIME .. if only I had TIME