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Some call it the biological cycle, the nitrification process, new tank syndrome or even the start-up cycle. They all are referring to the same cycle – The Nitrogen Cycle. This very important cycle is the establishment of beneficial bacteria in the aquarium and in the filter media that will help in the conversion of ammonia to nitrite and then the conversion of nitrite to nitrates.
Unlike nature, where the environment is open and has a constant supply of new, refreshed water, an aquarium is a closed environment. All the wastes excreted from the fish, uneaten food, and decaying plants have no where to go. If there is no mechanism to handle these waste products, your beautiful aquarium and all that is in it would die in no time at all
The system that nature employs in the open eco system can also be used in a closed environment such as an aquarium. This naturally occurring system is called the Nitrogen Cycle.
This process can take anywhere from 2 -8 weeks or longer depending on what strategy you use to cycle your tank. It is very important that you understand this process because it will help you to be successful in keeping fish and it should definitely improve your chances when keeping tropical fish.
The Nitrogen Cycle consists of 3 stages; Stage 1, the production of ammonia. Stage 2, the production of nitrite and stage 3, the production of nitrates. Each will be discussed below.
Stage 1 – Ammonia
In Stage 1 of the cycle, ammonia is released into the aquarium from uneaten fish foods, fish wastes and other biological processes. It is easily measured using an aquarium test kit and is the first reading you’ll get at the beginning of the aquarium nitrogen cycle. Ammonia is always being released into the aquarium and adequate biological filtration is needed to prevent the life forms from suffering because it is very poisonous to fish. Ammonia is thought to be the number one killer of fish in aquariums, most likely due to aquariums going through the nitrogen cycle. Measures must be taken to assure that these level are as close to zero as possible.
Stage 2 – Nitrites
During the second stage of the Nitrogen Cycle, nitrites are produced by the breakdown of ammonia. Nitrites are just as toxic as ammonia and must also be monitored closely. Once the bacteria in the tank have the ammonia under control, there will be a high nitrite spike. Having a sudden nitrite spike can kill a fish within a few hours.
Controlling the nitrite levels falls more within the lines of prevention although there are steps that can be taken to reduce the nitrite risk once the spike has occurred.
- The first step in preventing a nitrite spike is to keep your tanks clean. Seeing how the decay of food and waste will raise the chemical levels in your tank, a clean tank will help prevent the rise of un-wanted chemicals.
- The second preventative measure is to feed appropriately. Normal feeding is considered to be “only what your fish can eat in five minutes”. This will help in the prevention of food build up on the bottom of your tank.
- A third recommended preventative measure is to test water regularly. When I first start a new tank, I usually test the water 2-3 times a day at least. This way you can keep up with any changes in tank chemistry and can keep ahead of the problem. Knowing the exact chemical levels can save you major headaches in the future.
Prevention is the best method for dealing with a nitrite spike, but in case you do have a spike here are a few ways to deal with it.
- First you can add salt to the tank. Even though it is a fresh water tank, the amount of salt that you add will not be enough to change the salinity level of the water. The amount that you add needs to be one half ounce per gallon of water. Salt will also help fish that have been injured in a fight to heal, and fish that have parasites to get better.
- The second method for helping your fish survive a nitrite spike is to increase the oxygen level in the water. By turning up the aerator, the water will become saturated with oxygen and make it a little easier for the fish to breath.
- A third recommendation is performing a large water change. A normal water change is around 10%. By completing a large water change (30-40%) you are removing some of the contaminated water and replacing it with water free of nitrites reducing the saturation level of the nitrates. Prior to completing any large water change, make sure to give your fish the proper chemicals that they need to increase their slime coat. This will help them remain calm during this stressful time.
Stage 3 – Nitrates
The third and final stage of the nitrogen cycle occurs as the nitrites are broken down to form nitrates. Nitrates can be naturally removed by incorporating a trickle filter system that allows the anaerobic bacteria to consume the nitrates. A high level of nitrates always results from over production of nitrites which can be very harmful to your fish and flora.
So what is a safe nitrate level? Nitrates are measured in Parts Per Million (ppm) and for a normal operating tank the nitrate level should be under 25-ppm. If you are having problems with algae growth and everything seems to have a green tint to it, then you need to check your nitrate level. Algae growth is accelerated in a nitrate rich environment. Although plants use nitrates, the plants can only do so much. If there is a spike in the nitrate level, the plants may not be able to remove all of it in time. Also if you are considering breeding your fish you want to make sure that your nitrate level is 10ppm or less. This will prevent the fish from becoming sick and create a stable environment for the female’s gestation period.
There are a few simple steps that you can take to manage the nitrate level in your tank.
- The first step is regular cleaning. By removing the waste and uneaten fish food from the tank you can decrease the amount of nitrite production thereby reducing the nitrate level.
- The second step is to change your water. Performing a partial water change, around 10%, on a regular basis, is a good way to reduce the nitrate level, provided the water you are adding is low in nitrates. You can check with your local pet store for their suggestions on store bought water.
- The third method is to use live plants. The addition of live plants will reduce the amount of nitrates because plants absorb and use nitrates. If you have a high nitrate level, plants alone will not be able to get the nitrates under control quickly.
- Another method is to use a specialized filter or filter additive. This will help control and maintain the nitrate level as long as the filters are kept fresh and clean, and they are combined with other methods of controlling the nitrate levels.
Nitrates, in high numbers are very harmful for fish and plant life in an aquarium. Nitrates can harm the reproduction in fish and inhibit their breathing as well as cause a spike in the algae level of your tank, basically choking out the natural plants that you have growing there. As long as some basic steps are followed, it should not be difficult to control the nitrate levels in your tanks and keep all of your creatures healthy.