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How to cycle a fish tank? Aquarium cycle – Everything you need to know

10 10, 2023

Nitrogen aquarium cycle

Once we have a plan for what we want the aquarium to look like and what fish we want to keep in it, it's crucial to take care of the right conditions. Many beginner aquarists and fish keepers skip this step or do not do it thoroughly enough, which is a mistake. Therefore, we'll introduce the topic of the nitrogen cycle and aquarium maturation and help you to prepare your tank.

What is cycling a fish tank?

The nitrogen cycle is the most essential process in an aquarium. This process involves creating and maintaining a safe biological environment for all organisms in the aquarium. 

The aquarium cycle is a biological process that begins when a source of ammonia (such as fish waste or food) enters the aquarium. Thanks to beneficial bacteria and plants, ammonia is converted to nitrite. Nitrite is then converted to nitrate. Once nitrate is produced, the cycle is complete.

Aquarium maturation – how does it work?

The maturation of the aquarium is influenced by two processes that allow the nitrogen cycle to begin. The first process is the introduction and proliferation of nitrifying bacteria in your tank. The second process involves these bacteria converting toxic substances, such as ammonia, into nitrite and then into nitrate. The first few days are likely to have large fluctuations in parameters.

How to cycle a new fish tank?

What do you need to cycle? Before starting the cycling process, every new aquarium requires:

  • key aquarium components such as pumps, substrates
  • filtration elements (filters, filter media, sponges)
  • aquarium test kit (especially for amount of ammonia, nitrite, and nitrate)
  • fish food
  • filtered water (we recommend to use RO filter)

If tap water is not filtered, it is likely to contain harmful substances. One of them is chlorine, which disrupts the tank cycle and alters the pH. We have an alternative option if you don't have an RO filter. Specifically for the freshwater tank, we have created the AF Water Conditioner, which treats tap water and also provides vitamins and protective colloids. Combined with AF Remineralizer, which provides minerals, they create the right conditions for the aquarium.

Here are the 3 most popular ways to start a nitrogen cycle:

How to cycle without a fish? (freshwater and marine aquarium)

  1. This fishless cycle solution requires much more time than others, but is the most safe and fish-friendly way to cycle an aquarium.

    1. Equip the aquarium with the basic components we mentioned earlier. Filters, pumps, and substrate must be in place and working before the new tank will start maturation. All these elements will allow the bacteria to adjust to the aquarium conditions. In addition, the bacteria will have somewhere to settle and multiply. 
    2. Keep the pH at the right level. If the pH drops below 7.0 or rises above 9.0, it will cause ammonia levels to rise. There are many pH measurement tests available on the market.
    3. The time has come when we need to add a source of ammonia. A good choice is to add fish food. When the food begins to decompose, it releases ammonia. Since then, ammonia levels should be measured frequently. At this stage, the ammonia level should be 3 ppm. If the level is too low, add more food. If the level is too high (higher than 5 ppm), a water change should help.
    4. After a week, nitrite should be detected, start checking their level. They are formed from ammonia. So you need to take care of a stable level of ammonia at the same time as well. Otherwise, the nitrate level (which is formed from nitrite) will disappear, and then the whole process must be started again. If you observe a drop in nitrite levels with adequate ammonia levels, this is a sign to start using a nitrate test.
    5. Detection of nitrate means that the cycle is nearing to end. However, it is still necessary to provide the bacteria with a food source. Add half the amount of food from the first day.
      The tank is ready if the levels of ammonia and nitrite levels in the tank drop to zero, but nitrate levels are still detectable. You can now add a few fish to your tank, but you should still monitor the ammonia level. If ammonia remains at zero, additional fish can be added.

How to cycle a fish tank with plants? (freshwater aquarium)

If you want to choose this solution, you will need to stock up on nitrogen-containing fertilizers.

  1. Prepare the aquarium as in the previous method.
  2. It's a good idea to disinfect the plants before adding them. This preparation will prevent unwanted parasites and bacteria in the tank.
  3. The next step is to provide the plants with adequate light to help them photosynthesize. The lighting should be on for 10–12 hours during the day.
  4. Now is the time to add the fertilizer we mentioned earlier. Moreover, remember to make regular water changes to reduce algae.
  5. When observing the aquarium, if you notice an increase in algae, it is a sign that the cycle is closing. If there is too much algae, reduce the lighting. Remember to check ammonia, nitrite, and nitrate levels. When ammonia and nitrite are not detected, but nitrate are, it means that the nitrogen cycle is complete.

How to tank cycle with used filtration media? (marine aquarium)

  1. In this case, we will use one of the biological filtration media, on which there are already settled bacteria. So these elements must be taken from an already working aquarium. For these media, we can include for example: piece of rock, filter cartridge or ceramic rings. You can buy them from an aquarium store or from a friendly aquarist, but you need to be sure that the elements are not infected with parasites.
    If you want to make sure your filter media is not infected, we recommend using our Life Bio Fil. It is a natural biological filter media that initiates and accelerates the nitrification process.
  2. After a week, you will need a source of ammonia. Therefore, put some crabs and shrimps in the aquarium, these invertebrates are called the cleaning crew. Feed them every day, in very small portions. After a few days, they will start producing ammonia.
  3. Now start testing water parameters. This will help control the entire cycle.
  4. At some point, you will see a spike in ammonia, followed by a spike in nitrite. The moment you see a spike in nitrates, and at the same time, ammonia and nitrites should drop. This is a sign that the aquarium is ready.

How long to cycle a tank?

The maturation time of the tank lasts from 2 to 8 weeks. There are several factors that affect the timing of this process. E.g., size of aquarium, temperature of water, pH, and also type of aquarium. If maturation takes longer than you thought, don't panic, perhaps more time is needed.

How to cycle your aquarium quickly?

Aquaristic is a fast-growing field, so we have created many bacterial products to help speed up the cycle of your tank. Many products in our assortment will help you achieve this goal, ensuring a safe environment for your fish and aquarium plants.

For saltwater tanks, we recommend:

Bio S is excellent at reducing ammonia and nitrogen compounds, supporting the nitrification process. Pro Bio S contains specially selected strains of probiotic bacteria that initiate the process of reducing harmful nitrate and phosphate. -NP Pro is a medium for these bacteria.

We also recommend Hybrid Pro Salt, which contains nitrifying bacteria.

We suggest AF Life Essence for every freshwater aquarium, which takes care of freshwater fish and plants. In addition, it helps lower ammonia levels.