The nitrogen cycle is started once you add the fish.
When the fish start eating, they then produce waste and this then produces ammonia. Leftover food in the tank also produces ammonia, and ammonia is very dangerous to your fish. It burns the scales, their fins, and their gills and is one of the main causes of fin rot. In this article, I will explain how to do fishless tank cycling
What are the nitrogen cycle steps?
As the cycle continues, ammonia is then broken down by a
So now that we’ve seen how the nitrogen cycle works, how do we take care of the tank?
Doing regular water changes every few days will really help your fish. You need to do about 10 to 15 percent and this will help reduce the amount of ammonia in the tank which will help relieve some of the stress on your fish. When the tank is going through the cycling process it is ideal to do regular water testing. That way you can monitor the ammonia, nitrite and nitrate levels and you would also know when the cycling process is complete.
Using a freshwater test kit
You can use something like the API master kit and this would give you accurate readings of your ammonia, nitrite, and nitrate levels. It’s important to not overfeed your fish. The more you feed them, the more waste they produce, and this also adds to the ammonia levels in the tank. You can use a product such as F
How Long Does the Nitrogen Cycle Take?
With cycling a tank
patience is really the biggest factor, it does take anything between four to eight weeks for a tank to cycle properly, and during that time that can be very very stressful for your fish. So very careful maintenance of the tank is very important.
When Do You Stop Adding Ammonia?
In your first week, start by adding a small amount of ammonia to your fish tank, this can be done with urine or with store-bought ammonia (often found undiluted in the cleaning products section). You want your initial ammonia reading to be 0.5ppm.
Take note of exactly how much you needed to add to reach that and remember that it will take a while to cycle through so add in the morning and check in the evening.
Repeat this daily with an increase of 0.5ppm until your nitrite level reaches 0.5ppm also.
If you’re seeing your ammonia levels continue to rise without seeing the nitrite appearing, then stop adding ammonia and continue to monitor for the bacteria to catch up.
Remember the cesspool? If you keep adding ammonia you’re on your way to that stage, so patience is key.
Once your nitrite reading is at 0.5ppm, cut your ammonia down to 0.25ppm. This process will take about 7-10 days overall, and you should not add fish to the tank at this point because the nitrogen and ammonia levels will be too high for them to survive.
You want your tank to be between 77-86°F as this is the optimum temperature for the bacteria to grow, even if you need the temperature lower for fish. The pH of your tank also needs to remain fairly alkaline at 7-8. If you are doing the fishless cycling method, you’ll want to add plants before fish to help cut down the risk of the ammonia levels rising too high and killing them off.
You can jumpstart this process by adding media from an existing system as long as you didn’t have issues with disease. However, this includes any household fish tank or pet store aquarium. Many places will happily let you take an old filter sponge for free, and this is the perfect way to add a healthy bacteria colony to your tank. River or lake rocks are also a good source of suitable bacteria, and these can be easily dropped into the bottom of your tank.
How To Do a Cycle With Fish?
If you’ve already established your system, then you may need to cycle with fish. This process is a little more complicated as you can’t risk the ammonia levels becoming too high. This is often the case when you’re changing plants but not changing fish. You can cycle a system that has fish in it as your initial source of ammonia. Since your fish will immediately start producing ammonia you don’t need any other source.
During week one, feed your fish sparingly. You don’t want the food to rot and begin to produce excess ammonia. About 1 tbsp of food per 500L tank is acceptable. If you see algae forming at this time stop feeding them until the bloom dies back. Monitor your levels of ammonia and nitrites for the same numbers as the fishless for week one. This may take less time or it may take more depending on how big your system is and the number of fish.
What If The System Not Cycling?
Many growers find that no matter what they did and how many instructions they follow their system doesn’t cycle. Nitrate and ammonia levels continue to rise and it seems that they are either going to have to remove the fish or start over. This is the caveat with adding too much ammonia. When you start your system, too much ammonia can kill off the bacteria you are trying to cultivate, so there is nothing there left to grow and convert it into nitrite. You can continue to add a small dose of ammonia at this time. A level of 1ppm ammonia is enough to tip this scale, and you’ll want to stop adding ammonia since the bacteria is obviously not sufficient enough to cope with the amount.
The most common thing you’ll see if your system isn’t cycling is the initial ammonia spike, followed by a sharp drop-off. Nitrate and nitrite levels will continue to rise but ammonia never does. You may have a pH that is slightly high (above 7).
While you may have reached week 4 at this point and not seen any change in numbers, it’s actually a matter of patience. The pH is the key here, as long as it’s only a little above 7 (e.g 7.6) your system is still getting started. The other issue you may have is that your cycle isn’t getting enough air. The bacteria that convert nitrate to nitrite are naturally aerobic. This means that they need a good source of oxygen in the water to function. If there isn’t enough oxygen, anaerobic bacteria that perform the process backward may grow, increasing your nitrate levels and accounting for why you have high levels of both.
If you’re working with a flood system or only running your pump part of the time, run it constantly for a few days and check the numbers. The increased aeration may fix a bacterial imbalance and it may speed up the process if it’s a matter of time. In fact, if you’re only running your pump part-time you should expect cycling to take longer.
When the system does start to cycle, you will see a sharp and sudden drop in nitrates, so continue to monitor daily.
Common Mistakes With Cycling The Tank
It’s not just your cycling that can go wrong. There are lots of common mistakes and myths that people screw up their systems with then blame it on difficulty. Just thinking that you can set fish and plants up and let them go is a dangerous mistake. Constant monitoring for success. The system pH, temperature and nutrient (nitrite/nitrate) levels are all important in making it work.
If one of these is not balanced your system suffers and the whole thing might go wrong overnight. Overfed your fish? Ammonia levels rise, bacteria can’t keep up and suddenly your fish have ammonia poisoning and plants are dying because the pH is sky-high. Don’t believe for a minute you can simply “set it and leave”. This is by far the most common beginner mistake, so if you take anything from this section it should be monitor, monitor, monitor.
If you do see problems in your tank with monitoring you need to fix them, but you need to fix them properly. It’s easy to panic when you see a reading that isn’t right but trying to change things too quick will either kill your plants or your fish. For example, if your pH is off, never try and change it more than 0.5 a day. Any larger change will kill fish and it’s often a case of having the patience for the level to drop on its own. Ignoring problems also won’t make them go away.
Algae growth, for example, is a common issue. Nutrient-rich water and warm sunlight are prime conditions for algae growth which in turn can unbalance your pH. Shading is an ideal way to keep your algae down but if it starts to get very bad you’ll need to cover the tank completely and block out sunlight until it dies off. You can also consider adding algae-eating fish to your tank if you have space.
Feeding The Fish
Another common issue is letting your system get out of rhythm. This could be by not feeding your fish on a regular timetable or allowing your water temperature to vary too much. Constantly having a system in flux will damage your nitrogen cycle and will make it harder for everything to grow. If you can’t trust yourself to feed your fish on time or monitor temperature, consider automating your system so it’s done for you. This will stop the problem altogether and it will save your time.
Media And Gravel
The same is true of your media. For example, if you’re using gravel you may find you get a lot of algae under the stones which create the perfect environment for anaerobic bacteria to thrive. This upsets your whole system and will stop it cycling.
Stirring your gravel frequently is a great way to get around this. The same goes with coir decomposing and producing its own source of ammonia. You have to monitor even this to make sure it’s not a problem and replace or sanitize as needed.
Hi, my name is Sean, and I’m the primary writer on the site. I’m blogging mostly about freshwater and saltwater aquariums, fish, invertebrates, and plants. I’m experienced in the fishkeeping hobby for many years. Over the years I have kept many tanks, and have recently begun getting more serious in wanting to become a professional aquarist. All my knowledge comes from experience and reading forums and a lot of informative sites. In pursuit of becoming a professional, I also want to inspire as many people as I can to pick up this hobby and keep the public interest growing.
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