The Nitrogen Cycle & Water Quality
The Nitrogen Cycle
How the Nitrogen Cycle works is one of the most vital things you will ever learn in fishkeeping!
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Having a clean and established aquarium is your first priority before you bring your Axolotl home. There are several organic components at play here; Biological waste, Ammonia, Nitrifying Bacteria (two types), Nitrite and Nitrate. There are many well written, in depth articles on the nuances of interactions between these components but this will not be one of them. The section "Water Chemistry" will go over parameters for an established tank. For now let's stick with the basics- explaining the nitrogen cycle/how a tank cycles:
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First decaying matter in your tank such as Axolotl waste, old plant matter and leftover food start to break down. This process produces Ammonia (NH3) which is toxic to Axolotl and other aquatic organisms. Due to their semi-permeable soft skin your pet axie is more prone to these toxins. Ammonia build up in a tank will cause your Axolotl to fall ill, sustain burns, and in higher concentrations it is quickly fatal. "Cycling" an aquarium begins by the addition of Ammonia or an Ammonia source to the tank. This can be store bought straight Ammonia, rotting food, or for the advanced aquarist ONLY you can have a living fish as your source. You will want to bring the initial concentration of Ammonia up to 2-4ppm. Test your water until you notice Ammonia levels start to drop.
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Now the first type of Nitrifying Bacteria have colonized the biological media (sponges, ceramic or plastic beads etc.) in your fllter and these bacteria eat the Ammonia, turning it into Nitrite (NO-2). This compound is also toxic to fish, and makes breathing difficult. Build up of Nitrite in a tank will also cause illness, disease, and fatalities in high concentrations. The presence of a Nitrite reading in a cycling tank means you are halfway there! Continue dosing Ammonia to the appropriate level and test Nitrite as well until you notice it starts to drop.
This indicates the final step in the cycling process ihas begun. The last step is the growth of a second kind of Nitrifying bacteria which consumes and converts toxic Nitrite into relatively harmless Nitrate. When you can get a Nitrate reading on your cycling tank it means you are almost finished. When all of the Ammonia and Nitrite in your tank have been converted to Nitrate (Ex: Readings of Ammonia= 0ppm, Nitrite= 0ppm, Nitrate= 35ppm) your cycle is completed. Nitrate should remain below 20-40ppm in an established tank, which is achieved by regular weekly water changes of approximately 20% and it is removed when live plants use it as a nutrient. ​
In summation you need to add Ammonia to a new tank, wait for bacteria to colonize your filter and turn the Ammonia into Nitrite. The next step involves MORE waiting as a second type of nitrifying bacteria convert Nitrite into Nitrate. You then wait until levels of Ammonia and Nitrite read 0ppm and you have a high Nitrate reading before performing a 70% water change (change water until levels are well below 40ppm) and adding your Axolotl.​
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NOTE: ***This cycling process can take 4-12 weeks by itself, and 1-3 weeks with a "seeded" filter (a new filter that has had some media from an established filter containing both types of good bacteria added). ​Many common issues experienced by new Axolotl keepers can be avoided by fully cycling your tank before bringing home your new pet! CYCLE CYCLE CYCLE PEOPLE!
Water Chemistry
There's a lot more going on in your water than the surface shows. Ammonia, Nitrite, Nitrate, kH, gH, and pH are 6 water parameters that every aquarist should be familiar with. In this section i'll give a brief overview of each and detail the ideal range of each parameter for your Axolotl.
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To maintain healthy water quality you will need a liquid freshwater chemistry testing kit. I use the "API Master Kit" personally and it is approximately $38.00 CAD. Liquid kits are a bit more expensive than strip kits initially but have enough chemicals for many more tests in the long run and are FAR more accurate. Strip tests produce far less reliable results and should be avoided in favour of liquid test kits.
Note: This is a photo of a great water test result. Left to right- Ammonia 0.0ppm, Nitrite 0.0ppm, Nitrate 5-10ppm
Ammonia
Ammonia (NH3) is the product of animal waste, decaying plant matter and excess food breaking down. This chemical is toxic to fish, amphibians and other aquatic life. Concentrations of 1ppm or higher will kill your Axolotl in mere days, while it's presence in any concentration for a longer period of time will weaken the immune system and allow illness, disease, burns and subsequent infections to take hold. Ammonia is converted by nitrifying bacteria almost instantaneously into Nitrite (NO-2) in a healthy aquarium. A fully cycled, healthy aquarium should have an NH3 reading of 0ppm.
Nitrite
Nitrite (NO-2) is the toxic (even more so) product of Ammonia. Nitrite is only present in newly cycling aquariums or aquariums experiencing a "cycle bump". In a fully established aquarium the conversion from Ammonia to Nitrite to Nitrate is instant and we don't see it during regular testing. We can sometimes be alerted to the presence of Nitrite by Axolotl gasping at the surface as NO-2 has a suffocating effect. As with Ammonia, Nitrite concentrations of 1ppm or higher will result in quick death and it's presence in any detectable concentration should be an indicator of a damaged cycle. Small concentrations of salt are sometimes used in conjunction with an air stone to alleviate minor symptoms of Nitrite poisoning, but animals exposed to it for very long will fall victim to disease, illness and eventual (or not so eventual) fatality. Nitrite is converted to the final product in the Nitrogen Cycle, Nitrate.
Nitrate
Nitrate (NO-3) is present in all established aquariums. It is the final product in "The Nitrogen Cycle", and the one that you will be managing with your weekly water changes. Nitrate is harmless in small concentrations but can become toxic if levels are left to rise above 40ppm. Ideal range is 5-20ppm, with 20-40ppm being tolerable as well...basically the lower your nitrate level the better! In an appropriately sized tank that is stocked with a suitable amount of Axolotls whom aren't overfed a weekly water change of 20-25% should suffice to maintain good water quality.
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Some additional ways of removing Nitrates from the water column are: live aquatic plants, plants like Pothos or Bamboo which can grow in filter boxes with roots immersed, and chemical filtration products.
KH (Carbonate Hardness)
KH represents "Carbonate Hardness" and indicates how much carbonate is in your aquarium. This number is important because carbonate helps keep your PH stable by absorbing acid. KH is especially important to those using injected C02 as high KH when used in conjunction with C02 will prevent drastic PH swings. There are methods for raising KH (such as using biocarbonate of soda), but like other aquarium parameters you need to research methods, concentrations and volumes heavily before attempting to change your waters natural chemistry. Axolotl are very sensitive to changes in water quality, in addition to being sensitive to many over the counter products used to adjust these values.
Even if it is slightly outside of the ideal range- stable is best!
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GH (General Hardness)
GH is the General Hardness of your water. Many people are familiar with the "hardness" of their local water as there are sometimes visible indicators (ie- limescale in cookware or on pipes/faucets indicates hard water). PH can sometimes be a tell-tale for GH- soft water tends to be more acidic (lower PH) and hard water tends to be more alkaline (higher PH). API does sell liquid test kits for these values as well, although they don't come in the standard master kit like PH does.
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Axolotl prefer medium-hard water (210-320ppm or as it is sometimes measured 12-18 dH). GH is the water parameter that measures dissolved minerals in the water- soft has less, hard water has more. If your water is too soft your Axolotl can become pale and washed out in colour, indicative of anemia. If this is the case you will need to use means to raise the hardness of your water to a healthy level. Luckily this is one of the easiest values to adjust naturally! Adding limestone chips in a filter bag to your filter or crushed coral in a bag to the tank or the filter will raise water hardness.
PH (Per Hydrogen)
PH (Representative of per hydrogen or acidity) is one of the most important water parameters. All aquatic life has a preferred range and it is one of the most difficult parameters to adjust with a higher level of risk associated with adjustment errors.
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PH is a scale that runs from 0 to 14 and is as follows: 0-6.9 is acidic, 7 is the middle ground and is deemed neutral, 7.1- 14 is considered alkaline. Axolotls prefer a PH in the range of 6.5-7.5 but can do well at slightly higher or lower PH provided it is stable. I find my Axies have always done better in slightly alkaline water. Currently mine are kept at 7.8, and since I have a high GH/KH (and therefore a very stable PH), and healthy Axolotl I have opted not to alter mine. In my personal experience if your city has crazy water (mine has Ammonia, Nitrates, Chlorine and Chloramines out of the tap with a high PH) you might find Axolotl that are born and raised in that water do better than ones shipped in to local pet stores.
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PH also affects the toxicity of Ammonia- the higher the PH the more toxic Ammonia is. Keep this in mind when cycling a tank or experiencing a cycle bump and remember to always test all parameters weekly.
Many of the chemicals used to alter PH could be harmful or irritating to your pet Axolotl so only adjust in circumstances of drastic PH and do so with lots of research tempered by extreme caution. Variances and swings in PH, even if fairly gradual can be very stressful with sudden changes being fatal to most aquatic animals, Axolotls especially.
NOTES:
*Some changes to your tank can cause a "cycle bump" or small spike in Ammonia, Nitrite etc if the bacteria colony is diminished or new ammonia sources are added. These usually resolve in a week or so when the colony of bacteria adjusts to the new supply/demand. Some common causes for cycle bumps are; removal of gravel substrate, removal of large tank decorations, overly vigorous cleaning of the filter, or addition of new tank inhabitants.
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**All filter maintenance and cleaning of tank decor should be performed in a bucket of tank water. Using water straight from your tank prevents shocking your healthy bacteria colonies or wiping them out accidentally with chlorine/chloramines from the tap.
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***Many sources of tap water contain chlorine and/or chloramines. All water that comes into contact with your filter, your Axolotls or that you are using for water changes etc. needs to be treated with a high quality dechlorinator. "Seachem Prime" is my dechlorinator of choice as this product neutralizes chlorine AND chloramines (not all products do both well) in addition to being a lifesaver if you have an ammonia spike- Seachem Prime neutralizes Ammonia for up to 24 hours when used in a double dose.
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