The Nitrogen Cycle is the bio-geo-chemical cycle that converts nitrogen into multiple chemical forms through both biological and mechanical processes.
The process involves ammonification, nitrification, denitrification, and fixation; though nitrogen forms 78% of the earth’s atmosphere, it has very little biological process use. Nitrogen is a principal element in the nucleic acid DNA and RNA, crucial to all living things, including plant and animal kingdoms.
The Nitrogen Cycle is an unending process in which nitrogen passes through the atmosphere, soil, plants, animals, water, etc. The nitrogen changes its form to pass through different elements; in the atmosphere, it exists as a gas; in the soil, nitrogen oxide, and dioxide. It also takes the forms of ammonia, nitrite, and nitrate.
How and why Nitrogen Cycle is indispensable in an Aquarium Tank?
Clean water is fundamental for any aqua life to thrive; the Filtration in an aquarium can be mechanical, chemical, and biological. The Nitrogen Cycle deals with or processes the chemical and the biological part of aquarium water purification. In other words, the nitrogen cycle is the process that takes place in converting fish wastes from toxic to less toxic or non-toxic.
This biochemical process involves continual biodegradation from Ammonia to Nitrite to Nitrate. In this, nitrate is the least toxic nitrogenous compound; the permissible limit for nitrates in water is between 20 to 50 ppm.
The aquarium plants control the nitrates level in the water by absorbing, and the excess nitrates are taken care of by the periodic water changes.
Fish expels ammonia through their gills; urine and feces produce ammonia while decomposing; furthermore, the leftovers and decomposing plants produce Ammonia—the nitrifying bacterium, aerobic bacteria that convert inorganic compounds into their energy source. The Nitrification process requires two different microorganisms; bacteria or enzymes that convert ammonia into nitrites, Nitrosomonas, Nitrosospira, Nitrosococcus and Nitrosolobus, and the bacteria that convert nitrites into nitrates are Nitrobacter, Nitrospina, Nitrococcus.
Ammonia is noxious to fish and invertebrates or any aqua life; it can damage the gills and cause respiratory problems; at times, it can kill your fish and invertebrates.
Without a Proper Nitrogen Cycle, an aquarium would be a pool of toxic concoctions that cannot support any fish as an aquarium is a closed-loop ecosystem.
Hence, understanding the Nitrogen Cycle in an aquarium is the prerequisite for you to benefit from the fish-keeping hobby.
Ammonia in your aquarium
The Nitrogen Cycle – Time Line
To establish the first cycle in a new tank, it can take anywhere between four weeks to eight weeks to complete a fishless cycle to establish a good colony of Nitrosomonas & co and Nitrospina & co. Here, patience is the virtue; it is better to arrange and adjust all the necessary parameters in a tank without your fish and invertebrates than when they are in the tank swimming around.
We have seen that the Nitrogen Cycle involves three stages:
Ammonia and Ionized Ammonia are introduced through the bio-waste depending on the water pH. When the pH is towards alkaline, above seven, you will have Ammonia, and when the pH is towards acidic, below seven, you will have Ammonia ions. It continues to build till the colony of Nitrosomonas, Nitrosospira, Nitrosococcus, and Nitrosolobus forms.
Once the bacterial colony is entrenched, you will notice that level of Ammonia and ionized Ammonia goes down.
When the Ammonia level goes down, the nitrogen cycle enters stage 2. The nitrite level starts to rise; it continues to grow until the Nitrospina, Nitrococcus, Nitrobacter colony is ingrained in the tank enough to digest all the nitrites. You will see that the nitrite level starts to decline.
When the Nitrite level starts to decline, the Nitrate level will increase in the tank water; now, the cycle enters stage 3. The live aquarium plants absorb a significant portion of nitrates in the tank to produce amino acids for protein synthesis. Also, gravel substrates, rocks, and specific decors create room for an anaerobic bacterial colony that will digest nitrates into nitrogen gas.
Nitrates are allowed to build anywhere between 20 to 50 ppm, depending on the species; the best is to keep it under 20 ppm.
The Nitrogen Cycle with fish:
Fishless Nitrogen Cycle
There are few methods to start Fishless Nitrogen Cycle; whichever method you choose, you would want to invest in your tank, a quality test kit, and a filtration system up and running.
Fish food method:
It is the simplest method to start your Nitrogen Cycle. In this way, you begin to sprinkle good quality commercial fish food or shrimps just as you feed your fish; continue to add the fish food every day. As this uneaten food starts to decay, it will produce Ammonia; Ammonia’s accumulation will promote Nitrosomonas, Nitrosospira, Nitrosococcus, Nitrosolobus bacterial growth.
Instead of sprinkling the feed directly in the water, you can tie them in a sock or cheesecloth, or stocking. The advantage of using a sock or fabric will make it easier for you to remove the leftovers when you no longer need them in the tank.
This method is just the same as it occurs naturally; only you stimulate in an enclosed environment without harming any aqua life. For the feed quantity, you would either do the trial and error method or use an Ammonia calculator.
All the commercial fish feed package mentions the percentage of protein in the food; by entering daily food in grams with the tank’s volume will give you the quantity of food to feed per day.
The fish food method is the longest as we are trying to replicate the natural process. However, you could also use this time to quarantine your fish stock.
Adding Household Ammonia:
Household Ammonia is available in any pharmacy. It usually comes diluted, mentioning the percentage on the label. You would need a calculator to know how much Ammonia you need to add to your tank.
You can use a syringe to measure and add the required quantity of Ammonia.
I would advise you not to yield to your curiosity to sniff the content in the bottle. It can cause severe irritation of the nose, eyes, and lungs; in some cases, it can cause asphyxiation and even death.
Start adding Ammonia every day until it rises to 5 ppm or more, then measure for nitrites; just the moment the nitrites are measurable, reduce Ammonia’s dosing to 50% as soon as Ammonia and Nitrite touch zero ppm the tank has completed its Nitrogen Cycle.
Generally, 2 to 3 ppm is good enough Ammonia to host a good colony of bacteria that will be good to deal with your fish wastes, leftovers, and plant matter decays. When you use 5ppm or more Ammonia, it is quite large enough to handle a good aquarium stock.
Using the household Ammonia method is one of the easiest, safest and fastest ways to establish an adequate bacterial colony to handle your fish wastes and plant matter.
Ready Bio-kits for Nitrogen Cycle:
Seeding the aquarium tank:
Seeding the aquarium tank is for those who do not want to wait 4 to 8 weeks to add their stock to the fish tank. It is also a prevalent practice among aquarists. In this process, you use nitrifying bacterial colonies from an established aquarium tank. This method gives you a jump start on the Nitrogen Cycle; it only takes half the time to complete the cycle it would typically take.
Transfering nitrifying bacteria from an established aquarium tank can be used in both the Nitrogen Cycle with the fish and fishless.
Though traces of nitrifying bacteria reside in the water, the actual colony resides in substrates, rocks, porous material, decors, and filter media.
If you already have an aquarium, seeding the new aquarium tank with nitrifying bacteria becomes easier. If not, you may have to obtain it from your local fish store, friends, etc.
Transporting the seeding material should be done quickly to ensure Ammonia and Nitrite’s supply to the bacteria to keep them alive and multiplying. You can make sure of that by transporting the seeding material along with some water from the original aquarium tank.
You would also want to transport the seeding material quickly, not to alter the water temperature significantly.
Seeding with Substrate
Seeding with rocks and porous decors
Seeding with Filter Media
Pitfall in using seeding method:
Although using seeding media to jump-start the new aquarium tank with the Nitrogen Cycle can be hazardous if not properly taken care of.
If there is even a single diseased specimen in the primary aquarium tank, you could be starting the whole new aquarium tank with disease or parasites. You wouldn’t want to have an unhealthy and troublesome aquarium tank from the start.
Before starting the seeding, test for all the water parameters and possible diseases and parasites in the primary tank; collect your seeding material or place the filter media in the tank.
If you miss out on this point, you will not enjoy the fish-keeping hobby as you are supposed to.
Getting ready to add an Ammonia source
Irrespective of the method you choose to go with, you need to get ready with the following:
- An aquarium tank with dechlorinated water, Decors, Plants, a filtration system, and a heater if you live in a cold climate.
- Test the water for pH, dGH, KH, Nitrates, and Ammonia if any trace. These parameters are bound to change during the Nitrogen Cycle; hence, you would want to know where you started to see what parameters are changing; whether the values are increasing or decreasing for you to continue with the process.
- Maintain a notebook with all the parameters before and after you run a test every time.
- Keep the Filtration running throughout. The dissolved oxygen level should be optimal as the nitrifying bacteria are aerobic and need oxygen to thrive.
Troubleshooting – The Nitrogen Cycle:
Aquarium won’t start cycling:
Ammonia should be detectable anywhere between 3 to 5 days if you can’t detect any Ammonia while testing or it has gotten to a certain point and stopped cycling.
The reason could be that something in the tank absorbs Ammonia.
- It could be you have too many plants, and the pH is on the acidic side. When the pH is below 7, Ammonia converts itself into ionized Ammonia and gets absorbed by the live aquarium plants in the tank.
- Carbonates and bicarbonates are used during the nitrifying process; it helps to stabilize pH in the aquarium.
The simple remedy to raise both the carbonates and the pH is to add bicarbonate soda from your kitchen. Please do not confuse baking powder with bicarbonate soda. You want to keep the KH level above 5 to keep the nitrification process going.
After adding bicarbonate soda, test the pH level; you may not get the pH level rise directly proportional to the quantity of bicarbonate soda; other factors come into play as it is not directly correlated. Hence, keep checking every time you add the bicarbonate soda till the pH turns on the alkaline side.
High Nitrates level:
Many aquarists experience an unwarranted level of rising in nitrates during fishless cycles; when the nitrates go over 100 ppm, you could do two consecutive 50 to 60% water changes.
Ensure to use only dechlorinated water and keep the water temperature the same as the tank water before top-up.
To carry out a consecutive 50% water change, you need to remove 50% of the water from the tank, refill it with fresh dechlorinated water, and repeat the same process. In this way, you throw out largely the accumulated nitrates without disturbing the nitrogenous bacterias.
Ammonia level doesn’t drop:
If the ammonia level is not dropping, causes could be
- either you have not dechlorinated the water
- low pH
Using tap water directly without dechlorinating will not let the nitrifying bacteria develop; hence, you would want to ensure to dechlorinate the water every time you are topping.
When the pH level is below neutral 7, Ammonia stays ionized; the nitrifying bacterias cannot benefit.
Ammonia levels do not fall because also you could be cleaning the tank, substrate, and even the filter too often or too vigorously. As we have seen earlier in this article, these bacterias reside on the substrate, rocks, decors, filter media, etc. if you clean them too often or vigorously, there is a chance you are removing all the beneficial bacterias from the system.