Ammonia, Nitrite, Nitrates


When it comes to providing the perfect home for your scaly friend, cycling a tank and parameters will always come up. So what is cycling? and why does these names keep coming up? 

The goal in an aquarium is to achieve an environment in which the water can sustain your ideal colony of aquatic life. Fish and other aquatic life will create waste and that is typically in the form of ammonia. It is naturally occurring in every aquarium, typically from organic waste breakdown. Ammonia is toxic and is a common killer in aquariums. 

Water changes can remove ammonia, however, waste is constantly produced and broken down. The water volume in the aquarium is a constant whereas waste keeps increasing. That is not sufficient to ensure a healthy environment to live in. What levels of ammonia is healthy? Zero. Yes, in a stocked aquarium, the test kit should have a reading of 0ppm to ensure your aquatic pets can thrive. 

In order to achieve this, we need to understand the nitrogen cycle. So we introduce your friendly bacteria, nitrosomonas and nitrobacter. These types of bacteria are classed as nitrifying bacteria. They will help in the conversion of ammonia to harmless nitrates. 


Nitrosomonas in short will convert ammonia to nitrite and nitrobacter convert nitrite to nitrate. Similar to ammonia, nitrites are also undesired. They too are toxic to fish. Nitrites will inhibit the ability of your fish to carry oxygen in their bloodstream. Hence, in order to achieve an environment where there is zero ammonia and nitrites despite organic waste being constantly present, we need to have enough nitrosomonas and nitrobacter in the aquarium. 

The process of building up enough bacteria is known as cycling the aquarium. The process can be quite time consuming, waiting for colonies of bacteria to grow. There are various methods in which cycling can be done, with the quickest method being adding "seeded" filter media into your new tank. That is taking media from an already established tank for your newly set up one. The nitrosomonas and nitrobacter are already in the media, and can start colonising the new aquarium. 

Another factor to add into how long it'll take to cycle the aquarium is the source of ammonia. Nitrosomonas cannot populate the new aquarium without a source of energy, which would be ammonia. If there is a lack of ammonia in the aquarium, the Nitrosomonas would eventually die out as they don't have any "food". Hence, straight ammonia is sometimes added for this purpose. Adding other sources of organic waste is also another way. 

Now you've gotten all this done, how do we know when the tank is cycled? This is when the aquarium test kits come in handy. With our understanding of the nitrogen cycle, we would test for ammonia, nitrite and nitrate levels in the aquarium. Here are some scenarios that can happen:

Ammonia- Some Levels; Nitrite - 0ppm,;Nitrate- 0ppm. The tank is not cycled. Going by these readings, there is insufficient nitrosomonas to convert ammonia to nitrite. We are unable to know if there is enough nitrobacter as there is no nitrite to nitrate conversions. It is safe to assume there is insufficient nitrobacter as well since there is 0ppm of nitrate. 

Ammonia- 0ppm; Nitrite - Some Levels; Nitrate -0ppm. We're almost done, there is sufficient nitrosomonas to convert the ammonia to nitrite, however we have insufficient nitrobacter to convert the nitrite to nitrate. 

Ammonia-0ppm; Nitrite-0ppm; Nitrate-0ppm. The tank is not cycled. In this case  it would indicate there is either no source of ammonia or there is no bacteria to convert ammonia and nitrite. 

Ammonia-0ppm; Nitrite-0ppm; Nitrate- Some Levels. The tank is cycled! With these parameters, it shows us that the bacteria are converting ammonia to nitrite and nitrite to nitrate. Now we just need to do water changes to remove the nitrate build up from time to time.