Aquaponics systems can produce plants that can be harvested quickly because of the continuous amount of nutrients that the system provides to the plants. But before you can add the fish and more plants into the system, it is essential that the beneficial bacteria which produce nutrients for the plants is introduced and established. This process is called "system cycling." Generally, there are two methods of cycling a new aquaponics system, which we will discuss in this article to give you choices on what type of system cycling will work best for your new aquaponics system.
What is System Cycling in Aquaponics?
System cycling is the process of establishing a bacterial colony in new aquaponics systems. This process involves constantly introducing an ammonia source into the system, feeding the new bacterial colony, and creating a biofilter. The ammonia can be generated by the fish or can be added using other methods. Ammonia is required for the nitrifying bacteria to begin their work and reproduce.
The cycling progress is measured by monitoring the nitrogen levels. The nitrogen cycle converts the ammonia from fish waste and decomposing fish food into nutrients for the plants. However, in order for this conversion to take place, the nitrifying bacteria must be present. These nitrifying bacteria first convert the ammonia into nitrites and then into nitrates, which become food for the plants. Your new aquaponics system is considered fully cycled when the nitrate levels increase steadily and the ammonia level is less than one ppm. The nitrite level is zero ppm during testing.
It is important to note that the ammonia and nitrite levels will be high during the cycling process, which could harm the fish. Also, ensure that the system, including the fish tank and biofilter, is protected from direct sunlight before starting the cycling process.
These tools are essential in the cycling process. During cycling, you must monitor the ammonia, nitrite, nitrates, and pH levels of your system so that you know if these elements are within their acceptable range. If they are not, you can take corrective action immediately to avoid more problems. These cycling tools will also help you know when your aquaponics system is fully cycled and ready for more fish. These are the tools you need for cycling your aquaponics system:
- Freshwater Master Test kit for testing ammonia, nitrites, nitrates, and pH levels.
- Submersible thermometer to measure your water temperature.
Things to Consider in Cycling a New Aquaponics System
- Knowing your water condition is very important, so use a reliable water test kit. It is also essential that you familiarize the process of performing water tests and reading the results.
- If you use the cycling with the fish method, consider using an inexpensive fish as a sacrificial fish.
- Once your system is fully cycled, consider adding composting red worms to your grow bed.
- Avoid using aquarium products such as water conditioners, algae preservatives, and other products for pet fish.
- Do not feed much during cycling. Don't worry; fish can survive without food for a few days.
- Do not mess with pH.
Methods of Cycling
Cycling with fish
Cycling with fish is the old method of cycling new aquaponics systems and can take 25-40 days. It is because the nitrifying bacteria grow relatively slow in this method.
Steps on Cycling with Fish
- Start fish cycling by adding a few fish to the fish tank. Add only a few fish because too many fish will cause the ammonia levels to spike and will be harmful to the fish.
- Once your fish are in, feed them lightly to start producing waste and start the cycle.
- Monitor the ammonia, nitrite, and nitrate levels daily to ensure they did not get too high. If the ammonia level is more than 3.0 ppm, you will have to do a partial or complete water change to avoid an ammonia spike. Ammonia should remain below 3.0 ppm, nitrite below 1.0 ppm, and the nitrate level should increase over time.
- Continue monitoring ammonia, nitrite, and nitrate levels and replacing the water as needed until your fish tank is fully cycled. Your aquaponics system is fully cycled when your ammonia and nitrite levels remain below 0.25 ppm.
Speeding the Cycling with Fish Process
Alternatively, if another aquaponic system is available, it is extremely helpful to share part of the biofilter as a seed of bacteria for the new system. This greatly decreases the time necessary for cycling the system. It can also be useful to separately start a biofilter medium by continuously trickling a solution containing 2–3 mg/litre of ammonia for a few weeks in advance. The media would then function as a primer by simply incorporating it into the new aquaponic biofilter. A simple trickling system can be built by suspending a wide plastic crate of medium above a small tank containing the ammonia solution that is being circulated by a small aquarium pump.
Fishless cycling has become the most popular method of cycling, a new aquaponics system today. It takes a few days and offers more advantages over cycling with fish. First, the grower and the fish will endure less stress while cycling. Second, there are no fish involved in the process, so you don't need to be overly concerned when ammonia, nitrite, and pH levels go up.
Sources of Ammonia for Fishless Cycling
- Liquid Ammonia: If you plan to use liquid ammonia, make sure that it is pure ammonia (5 -10%) and water. Don't use ammonia with perfumes, soaps, colorants, or any other additives. These additives could be detrimental to the fish and plants.
- Ammonium Chloride (Crystallized Ammonia): This is effective as the liquid ammonia. You can purchase this from any aquarium supply store.
- Urine: Human urine or any animal urine is a good source of ammonia. To use urine as your ammonia source, you should put it into a sealed bottle for three weeks to allow the urine to turn into ammonia before adding it to your system. If you add fresh urine into your system, you will not be able to track how much ammonia is going into the system. Your ammonia levels will read very low with fresh urine at first but will suddenly increase or explode after a few weeks, which is not good for your system.
- Dead Fish: Using a dead fish as an ammonia source is not an ideal approach because of the danger of allowing other bacteria or chemical compounds to enter your system. Dead fish may also attract flies and other insects, which are not good.
Steps of Fishless Cycling
1. When your aquaponics system is ready, begin by adding an ammonia solution a little at a time to the fish tank until your reading from the ammonia test is -5 ppm.
2. Record the amount of ammonia it took to reach the -5 ppm and then add that amount daily until the nitrite appears at 0.5 ppm.
3. Once nitrites appear, cut back the daily dose of ammonia into half of the original volume.
4. Once nitrates appear at 5 - 10 ppm and nitrites have dropped to zero, your system is fully cycled, and you can start adding your fish.
Adding Plants and Fish
You can add plants to your new aquaponics system as soon as you start cycling. Adding plants right away will let them go through the rooting process early on. Initially, you may notice some signs of nutrient deficiency, but this is normal. But once your system is established and starts producing the nutrients, they will become healthy and bear good fruits or harvest. You can start adding the fish once your new system's ammonia and nitrite levels are below one ppm. Start by slowly adding a few fish to your system.
Conclusion: Which Cycling Method to Choose?
In choosing what cycling method to use for your new aquaponics system, one factor you need to consider is the availability of pure ammonia in your location. Fishless cycling might be the less complicated method, but the cycling method with fish will be your best alternative if you can't get pure ammonia. However, if pure ammonia is readily available in your location, then the fishless cycling method is an excellent choice because it is less stressful for you and your fish.
System cycling is essential for a new aquaponics system to create the right environment for your fish, plants, and bacteria. It can be a challenge, but it is a necessary part of the setup process. System cycling only needs to be done once, so once you're done, you will not have to deal with it again. But once you've successfully cycled your new system, all you need to do is regular maintenance, plant your favorite vegetables, harvest, and enjoy the fruits of your labor.