How to Cycle an Aquarium

Every body of water has millions of microorganisms that break down organic matter and the numerous compounds that are generated during the process. These compounds are then further broken down and recycled in an endless cycle. A process that we must recreate when figuring out how to cycle an aquarium.

Why Cycle an Aquarium

Aquariums are artificially created closed ecosystems, which makes them different from natural bodies of water such as lakes, rivers, and ponds. To begin with, the tap water we use to fill an aquarium has undergone extensive filtration and chemical treatment to effectively eradicate any microorganisms.

Secondly, everything that enters or exits the aquarium’s ecosystem is entirely within our control, to a certain extent; we only need to be aware of what belongs inside of an aquarium and what doesn’t.

When cycling a new fish tank, there are three stages of the nitrification process that we must develop to create a healthy colony of beneficial microorganisms that convert ammonia to nitrite and nitrite to nitrate, the final and least harmful compound.

Ammonia is initially produced when organic matter decomposes in water and is also excreted by fish. When ammonia is present, beneficial bacteria will begin to colonize, primarily inside of your filtration unit but also, to a lesser extent, in other porous surfaces and substrates.

Small concentrations of ammonia and nitrite, 1 ppm and 5 ppm, respectively, are both lethal to fish. Nitrate is generally safe for fish but it can be lethal at high concentrations, maintaining low concentrations through weekly water changes can guarantee that your fish enjoy a healthy and long life.

How to Cycle an Aquarium Chart

Fishless Cycle with Fish Food

A cloudy tank might result from cycling a new fish tank with fish food and the degree of cloudiness will vary according to the types of food you use. The cloudy waters will clear up, though, once beneficial bacteria establish themselves and begin to break down ammonia and nitrites.

When cycling a fish tank, utilizing fish food in the form of pellets or flakes with fewer additives will greatly reduce cloudiness; look for sources with high protein concentrations. Frozen blood worms and brine shrimp work well because they don’t contain ash, wheat, or any other additives.

Start by adding a tiny pinch of fish food to an aquarium that has been filled with conditioned water; it will take a few days for the fish food to start breaking down and produce ammonia. During this time, you should test the water for ammonia levels every other day.

The objective is to increase ammonia levels to 2 ppm while maintaining levels below 5 ppm because high levels of ammonia can wipe out beneficial microorganisms. The type of food and size of your aquarium will drastically affect the amount of food required to achieve 2 ppm; it is best to add fish food in small quantities while regularly testing for ammonia levels.

Then begin testing the water for nitrites once ammonia levels have reached 2 ppm; when nitrites are present, we now know that beneficial bacteria have started to colonize. When both the ammonia and nitrite concentrations have fallen to 0 ppm followed by a significant water change of between 50 and 75 percent to reduce the levels of nitrates that have accumulated, it will then be safe to add fish.

Add a few fish right away since beneficial bacteria require a steady supply of organic waste. It’s important to keep in mind that adding fish should be done gradually, a few at a time, to give the beneficial bacteria time to adapt to increasing organic waste loads.

This process will normally take 4 to 6 weeks to complete without the aid of nitrifying bacteria, although it may take a little longer in some cases before ammonia and nitrite levels drop to 0 ppm. To expedite this process, scroll down to How to Cycle a Fish Tank Fast.

Fishless Cycle with Ammonia

When using ammonia, it’s important that you use pure ammonia with no additives other than water or ammonia solutions specifically made for aquarium use. The latter may be your best option since it is prohibited to sell pure ammonia in some nations, such as Canada. Plus, commercially available ammonia may contain additional additives that can potentially harm your fish.

Once the filtration system is installed, configured, and operational within an aquarium that has been filled with conditioned water. Adding 4 drops of Fritz ammonia solution per gallon will increase ammonia levels by up to 2 ppm. If you intend on using a different brand, follow the manufacturer’s suggested ratio in the instructions.

If you’re using 100% pure ammonia, it’s recommended to add 1 drop for every 5 gallons of water at first, and then use a test kit to determine the ammonia concentration. If more ammonia is required, add a few more drops gradually until 2 ppm of ammonia is present. When ammonia is diluted with water, more is needed; for instance, twice as much is needed when using a 50% dilution.

It’s important to note that ammonia levels should never rise above 5 ppm, at this level ammonia will become toxic to the beneficial bacteria.

It will be crucial to use a test kit to measure the ammonia levels every other day throughout this period until nitrite is present, at which point you should add half the recommended amount of ammonia solution two days later.

When both ammonia and nitrite levels have reached 0 ppm followed by a significant water change of between 50 and 75 percent to reduce the levels of nitrates that have accumulated, it will then be safe to introduce fish.

At this stage, you shouldn’t wait too long before you introduce fish because the beneficial bacteria will need a constant supply of organic waste in order to survive. The Introduction of fish should be done in small batches to avoid overloading the nitrogen cycle, as it takes some time for the nitrification process to adjust to greater concentrations of ammonia.

This process will normally take 4 to 6 weeks to complete without the aid of nitrifying bacteria, although it may take a little longer in some cases before ammonia and nitrite levels drop to 0 ppm. To expedite this process, scroll down to How to Cycle a Fish Tank Fast.

Aquarium cycling ammonia nitrite and nitrate levels

Note: If you are already keeping fish in your aquarium, adding ammonia or employing the fishless cycle approach will likely result in their demise.

Cycling with Fish

Cycling with fish will require more attention to detail in order to protect the health of the fish during the earlier stages of the nitrogen cycle. It is advised to conduct regular water testing for the first 4 to 6 weeks in order to properly monitor ammonia and nitrite levels.

Depending on the size of your aquarium, add two to four hardy species of fish to a tank that has been filled with conditioned water. Avoid adding too many fish at first because it will take some time for beneficial bacteria to proliferate.

Feeding will be minimal during this time, and all extra food and waste must be siphoned out right away to prevent dangerously high ammonia levels from rising too quickly. Additionally, it will be necessary to perform daily or at minimum three water changes weekly by refilling 1/3 to 1/2 of the entire volume of water and lightly vacuuming the substrate to remove any extra fish waste and food.

Beneficial bacteria will grow much faster when the lights are off, keeping the lights off for a little longer than usual will expedite this process. Ammonia and nitrite levels will need to be tested frequently until they are reading 0 ppm, then it will be safe to add a few more fish.

More frequent water changes will be needed if the levels of ammonia and nitrites appear to be rising with each test; overfeeding and lack of cleaning practices may also be to blame.

This process will normally take 4 to 6 weeks to complete without the aid of nitrifying bacteria, although it may take a little longer in some cases before ammonia and nitrite levels drop to 0 ppm. To expedite this process, scroll down to How to Cycle a Fish Tank Fast.

How to Cycle a Fish Tank Fast

In addition to following all of the steps in cycling with ammonia, fish food, or with fish. Adding nitrifying bacteria from products like API quick start, which will provide your aquarium with the necessary beneficial bacteria from the beginning, can greatly accelerate the process and cycle a fish tank quickly. Additionally, when the lights are turned off, beneficial bacteria will also begin to grow more rapidly.

Utilizing products that contain live nitrifying bacteria can quite easily reduce the amount of time to cycle your aquarium within 1 to 7 days. However, the majority of quick start products claim that adding fish straight away is safe. In some circumstances, they are correct, but there are a few reasons that it may fail. Inadequate storage of these live organisms in warehouses, at home, or during shipping can cause live microorganisms to die off, and incorrect dosing can lead to increased ammonia levels.

The safest approach would be to simultaneously add an ammonia solution or fish food with nitrifying bacteria and then monitor the levels of both ammonia and nitrite. Once nitrite or nitrate levels are present, adding fish is assuredly safe because we know the nitrifying bacteria is working as intended.

Whichever method you choose, adding fish to a newly cycled aquarium should be done in small batches. Regardless of whether you utilized nitrifying bacteria or not, it does take some time for a sizable, robust colony of beneficial bacteria to establish themselves; colonies need to adapt to rising organic waste loads due to the presence of fish.

Best Fish to Cycle a Tank

Amazonian species of fish, including neon tetras, piranhas, silver hatchetfish, apistogramma, cardinal tetras, various catfish, and some species of corydoras are extremely sensitive to even very low amounts of ammonia.

While most teleosts, or members of the infraclass Teleostei, are significantly more tolerant of low levels of ammonia. Teleosts utilize a variety of techniques for ammonia detoxification, especially after eating. One approach that they employ is glutamine synthesis, which allows them to excrete ammonia as urea. These species also slow down the breakdown of proteins and amino acids, which decreases the amount of ammonia that they expel.

Other methods, such as volatilizing ammonia or actively pumping ammonia out of the body, are used by other species of fish to deal with ammonia. With the exception of some species of loaches, the majority of the fish that use these strategies are often absent from aquariums.

The best fish to cycle a new fish tank are small, hardy fish that can handle low amounts of ammonia and don’t produce a lot of ammonia. Fish from the following species are best suited for newly cycled freshwater aquariums:

  • Zebrafish (Danio Rerio)
  • Dojo Loach (Misgurnus Anguillicaudatus)
  • Corydoras and Catfish belonging to (Siluriformes)
  • Minnows belonging to (Cypriniformes)
  • Mollies (Poecilia Sphenops)
  • Swordtail (Xiphophorus Hellerii)
  • Siamese Fighting Fish (Betta Splendens)
  • Guppies (Poecilia Reticulata)
  • Giant Danio (Devario Aequipinnatus)
  • Black Skirt Tetra (Gymnocorymbus ternetzi)
  • Buenos Aires Tetra (Hyphessobrycon anisitsi)

Even in fish that can withstand low ammonia levels, prolonged exposure to ammonia or rapidly rising ammonia levels can be harmful to their health. These species are only capable of withstanding ammonia concentrations below 1 ppm for brief periods of time.

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  1. I wanted to thank you for this very good read!! I absolutely enjoyed
    every bit of it. I have you book-marked to check out new things you post…


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