Nitrogen Cycle 101
We are going to dive into the nitrogen cycle! We’ll talk about what it is, why it’s so important, how to establish it, and how to maintain it. A nitrogen cycle is critical for all aquatic beings, but in particular axolotls (which are the focus of this particular blog).
What is the nitrogen cycle?
The “nitrogen cycle” refers to the process of establishing bacterial colonies that process nitrogenous waste compounds. It is referred to as a “cycle” because the bacteria consume nitrogen (in the form of ammonia from waste) and convert it into nitrites. These nitrites are then converted by different bacteria into nitrates. Nitrates are the end product of the nitrogen cycle, which means that they are not processed into anything else. Instead, you remove nitrates through regular water changes. The infographic below depicts and elaborates on the steps of the nitrogen cycle.
Why is having an established nitrogen cycle important?
The nitrogen cycle is important because it processes the toxic nitrogenous compounds produced by the axolotls. Without this cycle of beneficial bacteria the tank becomes toxic; the ammonia produced by the axolotl via waste builds up and causes burns. Nitrites are toxic in any capacity and cause poisoning, but are fatal over 2 ppm. Nitrates over 40 ppm are toxic and can cause poisoning symptoms as well.
How do I establish a nitrogen cycle (cycling a tank)?
A nitrogen cycle is established through a fishless cycling process. This means that the axolotl will not be in the tank during the cycling process (it is toxic, harmful, and often fatal to cycle with them in the tank). To establish the cycle you will mimic the axolotl’s waste by manually dosing ammonia to 2-3 ppm. Testing (with an API freshwater master test kit preferably) should be done every 24 hours after dosing ammonia. When the ammonia drops close to zero ppm, redose to 2-3 ppm.
At the beginning, the ammonia takes a long time to process because there are no beneficial bacteria to process it yet. Once the ammonia starts processing, you will see the appearance of nitrites and nitrates.
The nitrites dropping to zero is the longest waiting period of the entire cycle, but keep dosing ammonia and you’ll power through! The nitrates will be ignored until the very end of the cycle (unless maxed out at 160 ppm and then you will want to do a water change).
To complete the cycle a 3 day test will need to be passed. This entails having 3 consecutive days of zero ammonia, zero nitrite, and at least the presence of nitrates (but they are typically high ppm by the end of the cycling process).
Once the test is passed, 50% daily water changes should be performed to lower nitrates to 5-20 ppm before the axolotl can go in. If a heater was used, decrease the heater by a few degrees a day to avoid shocking the beneficial bacteria.
We have a cycling guide that can be found..
On Facebook: https://www.facebook.com/groups/3072360599567622/permalink/3330214380448908
On our website: https://www.libertylandaxolotlrescue.org/cycling-guide
What maintenance is required after the cycling process?
Even after your cycle is established and your axolotl is in the tank, there’s still maintenance to keep in mind!
As the bacteria process the ammonia produced by the axolotl it will be converted ultimately into nitrates. The nitrates should be maintained under 20 ppm, so regular water changes will be necessary. It’s recommended to test at least weekly. The percentage of water changed out will be determined by the level of nitrates present at that time. If at or over 20 ppm a 50% water change will be needed. When doing a water change remember to keep the water temperatures roughly the same, and don’t forget your Seachem Prime (or other safe, non-aloe-containing dechlorinator)!
If at any point the cycle “crashes” (indicated by the presence of ammonia and/or nitrites) please tub the axolotl(s) and perform a “mini cycle”. A mini-cycle consists of dosing ammonia and testing the same way you did when establishing your cycle the first time, but it doesn’t take nearly as long to fix itself as it would to cycle from scratch again.
Questions? Reach out to our team on Facebook and ask us how to join our private Axolotl Help Facebook group!
