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Cycling vs. Seasoning an Aquarium

Hey, fishy folk!

Today we're going to talk about the difference between cycling and seasoning your aquarium.

I'm sure you've hear of 'Cycling' your aquarium.... but 'Seasoning'?

Setting up a beautiful aquarium is a dream for many of us.

However, before introducing fish and other inhabitants to their new aquatic home, two essential processes come into play: cycling and seasoning.

Both cycling and seasoning serve the purpose of preparing the tank environment for its future inhabitants, but they differ significantly in approach and purpose.

Let's break it down.


CYCLING an Aquarium

Cycling is the process of establishing a healthy beneficial bacterial colony in your tank that can break down the waste products of your fish and plants. This is essential for keeping the water quality high and preventing ammonia and nitrite spikes that can harm or kill your fish.

Cycling usually takes 4 to 6 weeks, depending on the size of your tank, the type of filter you use, and the number of fish you have. You can cycle your tank with or without fish, but we recommend doing it without fish to avoid stressing them out.

Beneficial Bacteria Colonization

The success of the cycling process heavily relies on the establishment of beneficial bacteria. These bacteria play a vital role in breaking down ammonia, a highly toxic substance to fish.

Two types of nitrifying bacteria are involved in the process: Nitrosomonas, which convert ammonia into nitrites, and Nitrobacter, which further convert nitrites into nitrates.

To kick start the cycling process, aquarium owners can use different methods, such as the fishless cycle or the fish-in cycle.

The fishless cycle involves introducing a source of ammonia (ammonium chloride or ammonium sulfate) into the tank without fish. This allows the beneficial bacteria to colonize without causing harm to fish. We often use Seachem Stability to kick-start this process.

Adding filter media, plants, decorations, and substrate from an existing tank also helps this process get started. Remember.. the beneficial bacteria you need lives on surfaces! Not in the water.


The fish-in cycle, on the other hand, involves adding a few hardy fish to produce the ammonia needed for the bacterial colonization. However, this method requires close monitoring of the fish and water parameters, as fish may be subjected to temporary ammonia and nitrite spikes.

Guppies, Mollies and other livebearers are the usual fish chosen for this process. Many Kilifish and ricefish are also selected for their hardiness and tolerance of fluctuating parameters.

You should know, though, the Fish-in method is controversial and is not recommended personally by us.


Here's the science of what's happening during a Cycling:

Stage ONE: Ammonia to Nitrite Conversion

As the beneficial bacteria start to multiply and populate the tank's surfaces, they begin converting ammonia into nitrites through the process of nitrification.

Nitrites are also harmful to fish, even at low levels, but their presence indicates that the cycling process is progressing.


Stage TWO: Nitrite to Nitrate Conversion

The second stage of the nitrogen cycle involves the conversion of nitrites into nitrates by a different group of nitrifying bacteria.

Nitrates are far less toxic than ammonia and nitrites, but high levels of nitrates can still be detrimental to fish health, leading to issues like stress, reduced immune function, and stunted growth.


Regular Monitoring

Throughout the cycling process, diligent monitoring of water parameters is essential. Test kits are available to measure ammonia, nitrite, and nitrate levels to ensure that the beneficial bacteria are actively breaking down toxic substances.

Water changes will be necessary to keep ammonia and nitrite levels in check during the cycling process.

We like using simple multi- test strips. 


Cycling Duration

The cycling process can take anywhere from four to six weeks or more, depending on various factors, such as tank size, filtration capacity, and the efficiency of the beneficial bacteria population.

Patience is key during this phase, as rushing the process can lead to problems later on when fish are introduced.


How to know when your tank is Cycled

This is important because you don't want to add more fish or plants until your tank is fully cycled and ready. The easiest way to tell if your tank is cycled is to test the water for ammonia, nitrite, and nitrate levels. You can use a liquid test kit or test strips for this purpose.

✅ A cycled tank will have zero ammonia and nitrite levels, and some nitrate levels under 40ppm.

This means that the beneficial bacteria have converted all the ammonia and nitrite into nitrate, which is less toxic and can be removed by water changes or plants.

A cycled tank will also have a stable pH level, and a little bit of algae growth.

✅ If your tank is not cycled yet, you will see some ammonia and nitrite levels, and little or no nitrate levels.

This means that the beneficial bacteria are still growing and not able to handle all the waste in your tank.

You will also notice fluctuations in pH level and possible algae blooms. The water might also get a little cloudy, and smell nasty. Not like good clean dirt... but like nasty pond water.

✅ If your tank is not cycled yet, don't panic. Just keep testing the water every few days and be patient.

As we mentioned before, you can also add some bottled bacteria products or some filter media from an established tank to speed up the process.

But don't add any more fish or plants until your tank is fully cycled.. you'll just end up with dead things and heartbreak.


SEASONING an Aquarium

Seasoning an aquarium is the method of establishing a mature and stable ecosystem in your tank. It involves growing live plants, algae, and microorganisms that can help absorb and process the waste products of the fish and other inhabitants.

Seasoning an aquarium is different from cycling an aquarium, which only focuses on cultivating beneficial bacteria that can break down ammonia and nitrite.

Seasoning an aquarium takes longer than cycling an aquarium, but it provides more benefits and resilience for the long term health and well being of the fish and plants.

It's a tougher, more mature tank.... and can handle more of the stuff we'll throw at it.


How do you season your tank?

There are different ways to season your tank depending on what kind of items you want to add to your aquarium. Here are some general guidelines for using different types of items:

✔ Live plants can enhance the appearance and function of your tank by providing oxygen, shelter, and natural filtration.

It's simply the very best thing you can do to elevate your ecosystem.

To use live plants to help season your aquarium, you should rinse them thoroughly under running water and remove any dead or damaged leaves or stems.

You should also add as much plant matter as you can. All of it will boost your tank's 'Immune system'.

This is one of the guiding principles behind the Walstad tank movement.

More plants = More stability.

✔ Rocks & other hardscape elements can add texture and structure to your tank and create hiding places for your fish. They can help season your aquarium however, they can also alter the pH and hardness of your water depending on their composition. More on that in a bit.

Adding hardscape elements increases the surface area beneficial bacteria, algae, and bio-films can grow on... thereby increasing your tank's resiliency.

Before adding rocks, you should scrub them with a brush under running water and remove any dirt or debris. You should also test them for their effect on water chemistry by placing them in a bucket of water for a few days and measuring the pH and hardness before and after.

You should avoid rocks that contain calcium carbonate or other minerals that can raise the pH or hardness of your water too much. You should also avoid rocks that have sharp edges or metallic components that can injure your fish or rust in the water.

✔ Driftwood can add a natural look and feel to your tank and provide shelter for your fish.

However, it can also leach tannins into your water that can lower the pH and make the water tea- stained.

Many people seek this phenomenon out in order to harness the protective properties that tannins produce for their fish.

If you are not one of those people, then be sure to properly remove most of those tannins beforehand:

To prepare driftwood, you should boil it in a large pot of water for at least an hour. Change the water several times until it runs clear. You can also soak the driftwood in a bucket of water for a few days until it sinks to the bottom. You should also avoid driftwood that has sap or resin on it as it can be toxic to your fish.

Here's how we start tanks on their journey to a 'seasoned' ecosystem:

1. Choose a suitable tank size, filter, substrate, and décor for the desired fish and plants.

2. Fill the tank with dechlorinated water and set up the filter, heater, and other equipment.

3. Add a ton of live plants that are compatible with the water parameters and lighting conditions of the tank. We often choose plants that grow quickly and don't need planting. Think: Pearlweed, Guppy Grass, Hornwort, Water Sprite, Brazilian Pennywort.

4. Add some sources of organic matter, such as botanicals, driftwood, or leaf litter to the tank. These will serve as food for the microorganisms and algae that will colonize the tank.

5. Wait at least 4 to 6 weeks before adding any fish or other animals to the tank. During this time, monitor the water quality regularly and perform partial water changes as needed. The water should have low levels of ammonia, nitrite, and nitrate, and a stable pH and temperature.

6. Add fish or other animals gradually and in small numbers. Avoid overstocking or overfeeding the tank. Remember: 1 fish to 10 plants, not 10 fish to 1 plant.

7. Those quick growing plants you added in at the beginning? They should have long since taken over the tank. Now that their role in cycling the tank is through, you can always remove them easily and add in a ton of new plants if you would like to.

This is typically when we add in our 'permanent' plants such as Anubias, Crypts, carpeting plants and Bucephalandra. These are a little more sensitive, and slower- growing, so we save them for last. 

Remember to over plant to season that tank!

8. Time. Seasoning takes time. I find the expectation of 3-6 months to be appropriate. Your tank should be robust and the bacteria strong by then!

Why 'Season'?:

- Natural filtration! Plants, algae, and microorganisms absorb and process the waste products of the fish and other animals.

This dramatically reduces the need for frequent water changes and improves the water quality and clarity.

- Oxygen! Plants and algae produce oxygen through photosynthesis. This increases the dissolved oxygen level in the water and support the respiration of the inhabitants. 

When your water is well- oxygenated, a lot of common issues like cycle crashes, fish suffocation, and bad bacterial growth never occur.

- Food! For your fish, shrimp and snails-- plants, algae, and microorganisms can serve as sources of nutrition and supplements. This can reduce the need for your input (and possible over-feeding) and enhance the health and growth of the fish and other animals.

- Shelter! Plants and décor will create hiding places and territories. This can reduce the stress and aggression of fish and other animals and increase their comfort and security... Leading to better coloration, breeding, and awesome natural behaviors!

Cycling or seasoning?

If you cycle a tank properly, stick around...  it'll probably season itself anyway.

Many hobbyists choose to let their tank 'season' for a few months before introducing fish.

This is what we recommend for sensitive species such as Neocaridina Dwarf Shrimp. Have a riot of plant growth and layers of ecological function going.

Just 'Cycling' a tank is not enough.

 If you’re looking to establish a healthy environment for your aquatic life without causing undue stress to your fish, check out Vincent's blog post titled ‘How to Cycle a New Aquarium Without Stressing Your Fish’!.

Cycling and seasoning are both essential processes that prepare an aquarium for its inhabitants, but they serve different purposes. Cycling focuses on establishing beneficial bacteria to create a biologically balanced environment by converting toxic ammonia and nitrites, while seasoning ensures that the water is free from harmful chemicals, providing a safe and stable ecosystem for fish, invertebrates, and live plants.

By understanding the importance of these processes and following the appropriate steps, aquarium enthusiasts can set up a thriving, healthy, and sustainable underwater world for their aquatic companions, fostering a beautiful and enjoyable hobby for years to come.


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