Tag Archives: aquarium nitrogen cycle

5 Tips for the Fastest Fish Tank Cycling

Fish tank cycling can be a slow (and painful for some :P) process.  It might take up to 6~8 weeks to finish.  In the case of fishless cycling, some people might become impatient.  They just can’t wait to get their fish. There are certain things we can do to finish the aquarium nitrogen cycle a lot faster.

Reason for the slow Fish Tank Cycling

All the new fish tanks start with near zero beneficial bacteria of both types.  (Nitrosomonas for converting ammonia, and Nitrobacter for converting nitrite).  It takes time for them to multiply to a level where they can make an impact on the ammonia and nitrite.

More importantly, Nitrobacter will not even start to grow in number at all until there is nitrite in the water. For nitrite to appear, there must be enough Nitrosomonas to feed on and convert ammonia first. It can take 2~3 weeks before Nitrosomonas grow into sufficient number to provide nitrite for Nitrobacter.  It is a bottleneck right there to slow everything down.

We should make both stages starting simultaneously from the beginning.  The whole aquarium cycling can be a lot faster.

Three Tips to Speed up Fish Tank Cycling

1. A good filter
2. Heavy bacteria seeding
3. Higher water temperature
4. Higher oxygen level
5. Keep nitrate low

A Good Aquarium Filter

Since most of the aquarium nitrogen cycle bacteria reside on the filter media, it is essential to have a good aquarium filter.  A good filter means it not only has plenty of filter media for massive bacteria colony, but it also has high water flow rate.  Canister filters have the most filter media, and it is highly efficient for biological filtration.

Whatever filter system you choose for your aquarium, get one that is rated higher than your fish tank size is also a good idea.  The higher size fish tank the filter is rated for, the more filter media and more flow rate it has.  You can never have too much filtration in a fish tank.

Heavy Bacteria Seeding

To have some beneficial bacteria to start the aquarium nitrogen cycle will undoubtedly speed up the fish tank cycling. More importantly, to have both Nitrosomonas and Nitrobacter to begin the cycle from the very beginning can be a tremendous jump start.  Because it eliminates the waiting period for nitrite to appear.

Media from well-established aquariums

Traditionally people seed bacteria by using something from an already established aquarium. It can be a decoration or some gravel. The best thing to use in this case is a piece of filter media. Most of the beneficial bacteria colonize the filter media. By placing a piece of filter media from a well-established aquarium into a new filter, you can give quite a jump start to the aquarium nitrogen cycle.  Since not everyone has access to a well-established aquarium, this form of bacteria seeding might not be available.

Bacteria in a bottle

Nowadays, there are commercially available bacteria seeding products.  They are great for the jump-start the aquarium nitrogen cycle in new aquariums if you are willing to spend a little extra money.

There were some old bogus products with incorrect species of land-based bacteria in them. When you use those bogus products in an aquarium, at first the tank might seem to be cycled quickly.  But it will not last.  Because the land-based bacteria will drown in the water eventually. The result is the user must keep dosing those products to keep the aquarium nitrogen cycle from crashing. Due to the widespread of such bogus products in the past, many people believe all bacteria seeding products wouldn’t work. This is a misconception and old news.

Dr. Tim identified the correct species of bacteria and came up with a way to store them in a bottle in liquid form.  The first proven working product was Bio-Spira. It was not long before Tetra re-branded the same product into Tetra SafeStart which was more widely available and many aquarium hobbyists have successfully used it to quickly cycled their aquariums. The very same product is now in even more different bottles with different names. Dr. Tim’s One and Only is just another example.

These commercially available bottled bacteria are all proven working after tried by many fish keepers.  They are meant for the cycle with fish because most people are not patient enough to do the fishless cycling in an empty fish tank.

I have personally used Tetra SafeStart twice for the fishless cycling with pure ammonia on two occasions. In one case, it cycled my fish tank in just one week.  In the other case, it cycled the fish tank just 24 hours after the dosage.  It was amazing.  In both cases, the fish tank was cycled permanently.  Both ammonia and nitrite were 0ppm with an increasing amount of nitrate.

There were plenty of good reviews from other fish hobbyists before I even tried Tetra SafeStart.  The good results were no surprise to me.

When you use a commercial bacteria product, make sure you get a bottle that is rated higher than your fish tank.  The bigger the bottle, the more bacteria it has.  A lot of these products require the user to shake the bottle extensively before using.  Make sure you do not skip this step.  You must also dose the entire bottle in one go since the product will start to expire after you opened the seal.

Higher Water Temperature

Like most bacteria, both Nitrosomonas and Nitrobacter love warm water. In the case of fishless cycling, you may turn the aquarium heater up and raise the water temperature to be middle or high 80F.  It will speed up the multiplying of the beneficial bacteria. High temperature can also increase their appetite for ammonia and nitrite. Although it will not make the day and night difference in the total time required, it will certainly shorten it to some degree. Every little help counts when you can’t wait to get your hands on the new fish, right? 😛

Higher dissolved oxygen level

Both Nitrosomonas and Nitrobacter require oxygen to multiplying. A rich oxygen environment will undoubtedly help them grow faster.  Therefore, it shortens the fish tank cycling time. You can quickly achieve this by turn up the aquarium air pump and add more air stones. It is also required if you use higher temperature from the previous tip.   The warmer water holds less oxygen.

Keep Nitrate Low

The production of nitrate is acidic.  As more nitrate appears, it slowly eats away at the water buffer.  You might see the water PH slowly drop.  Once the water buffer is all gone, then there will be a sudden PH crash.  You might see the water PH go from 7 to 5 or even lower in one day.  When it happens, the acidic environment is not ideal for bacteria growth.  The fish tank cycling might be slowed or even stalled.  Do a partial water change to reduce nitrate concentration, and to restore water buffer at the same time is beneficial.

You only need to do the partial water change when there is excessive nitrate.  Partial water change too early will reduce ammonia and nitrite, which is not a good idea.


There is no set time for how long it will take to cycling fish tanks.  Each case may vary due to unpredictable variables.  Even when you use a live bacteria product for heavy seeding, it could be different every time.  Each bottle might give different results due to the way the product was transported, handled, and stored.  It affects the bacteria concentration in the product.

By applying all of the tips to speed up aquarium nitrogen cycle, you will at the very least be able to get the fastest results you can get.

Aquarium Nitrogen Cycle In Fish Tanks

Aquarium Nitrogen Cycle is perhaps the most crucial knowledge in fish keeping hobby. It is essential for the survival of fish in a captivity environment. Without continuous nitrogen cycle, most fish will drop like flies within weeks.  Learning aquarium nitrogen cycle is the very first step to keep aquarium fish like a professional.

What is an Aquarium Nitrogen Cycle?

The nitrogen cycle in an aquarium is the naturally occurring process of converting the toxic ammonia (NH3) to nitrite (NO2).  Then it turns the even more toxic nitrite to relatively harmless nitrate (NO3).

Ammonia (NH3) —>>> Nitrite (NO2) —>>> Nitrate (NO3)

What is ammonia?

Ammonia is a form of the nitrogen compound. It is toxic. It will cause burn to the fish’s gills in even the slightest amount.  The continuous exposure to just a tiny trace of ammonia will eventually kill the fish. Moreover, ammonia poisoning is one of the leading causes of fish dying in home aquariums.  It is especially true for newly set up aquariums. In a healthy aquarium, the ammonia concentration should be absolutely 0ppm (part per million).

Where is the ammonia from?

Almost all live organisms on the planet earth give off ammonia as a waste. Fish is no exception. The fish produce ammonia directly through the gills on a constant basis.  Their poop also produces more ammonia when it breaks down. All the other organic matters in the aquarium such as uneaten fish food, decay plants, and in some cases dead fish, also contribute to more ammonia in the water.  It is not a problem at all in a natural environment with a nearly unlimited amount of water.  (e.g., rivers, lakes, oceans).  Ammonia is not going anywhere in a closed system such as in a home aquarium.

How to remove ammonia?

Water Change alone never removes all ammonia

You can certainly try to remove ammonia manually from an aquarium by doing water changes.  This method does not remove all of it.  It is not a permanent solution.  Ammonia is produced on a constant basis in an aquarium as long as there is fish in it. Even if you do a 100% water change (not recommended) every day, ammonia will always build up between two water changes. You will never be able to keep it at 0ppm with water changes alone. This is where aquarium nitrogen cycle comes in.

A cycled aquarium takes care of ammonia and nitrite on a constant basis

We call a well-established home aquarium a “cycled tank.”  There is a species of waterborne bacteria called Nitrosomonas feed on ammonia as a food source. They convert ammonia to nitrite as a result. Nitrite is just as if not more toxic than ammonia. A second species of waterborne bacteria called Nitrobacter will come in and feed on nitrite as food. The result is the harmless nitrate. Both species of beneficial bacteria will continue to grow in number in an aquarium.  Until the point, they reach a balanced level where their combined appetite cancels out the production of ammonia and nitrite. As a result, all the well-established aquariums always have 0ppm readings on both ammonia and nitrite, with an increasing nitrate.

It is a good idea to cycle a fish tank before getting any fish

Both species of beneficial bacteria exist naturally in the water.  However, the number of them in any newly set up aquarium is always low.  It is nowhere near sufficient enough to keep ammonia and nitrite both at zero ppm which is required to keep your fish alive. The moment you add fish to a new fish tank, the ammonia level will start to rise.  It will never be 0ppm until you have cycled the tank. Furthermore, the fish will usually die from ammonia poisoning before the aquarium cycle is complete.  Because it often takes many weeks or even months before there are enough good bacteria. The solution is simple. You need to have sufficient amount of Nitrosomonas and Nitrobacter bacteria in a new fish tank before adding fish.

The Aquarium Nitrogen Cycling

The process of “growing” efficient amount of Nitrosomonas and Nitrobacter in a newly set up fish tank is called cycling an aquarium.  Or fish tank cycling. It is the safest way to make sure your new aquarium is ready.  So it can handle the amount of ammonia produced by the fish before you even add the fish.

A lot of fish beginners took the wrong advice of letting the fish tank sit for some days. They believe all this sitting will prepare the fish tank for fish. Having an empty fish tank full of water will achieve nothing even if you let it sit for many years. Since the beneficial bacteria need a source of ammonia to begin their growth, the aquarium nitrogen cycle won’t even start until you add a source of ammonia.

The three most common methods to cycle fish tanks

1. Fishless Cycle with pure ammonia

2. Fishless Cycling with fish food, or raw shrimp and raw fish

3. Cycle with fish (Fish-in Cycle)

Fishless Cycle with Fish Food

Since not everyone has access to pure ammonia, cycling with fish food or raw fish is another way to do a fishless cycling if you do not wish to cycle with fish. It is a slower and messier way to start aquarium nitrogen cycle.  However, it gets the job done.

To cycle a fish tank with fish food or raw shrimp or fish, you first need to set up an aquarium

Additional supplies you need for the cycling with fish food is
1. Fish food or raw fish/shrimp
2. a water test kit

Things to know before cycling aquarium with fish food (or raw fish/shrimp)
Flakes are easier to break down and to produce ammonia quicker than pellets. In the case of using raw fish or shrimp, it is faster if you chop them into smaller pieces.

Four Phase of cycling with fish food (or raw fish/shrimp)

Stage I. Waiting for the organic matters to break down to produce ammonia
Phase II.  There is ammonia in the water. Wait for nitrite to appear.
Stage III. Both ammonia and nitrite can be detected. Wait for nitrate to appear.
Stage IV. There is now a reading on nitrate. Wait for ammonia and nitrite both reach 0ppm.

Steps for cycling with fish food (or raw shrimp/fish)

Step 1. Make sure set up the tank is set up correctly and everything is running. The most important thing is the filter system. It must be running 24/7. The aquarium water must be treated with aquarium water conditioner to neutralize chlorine in the tap water, or it will kill the very same beneficial bacteria you try to have.

Step 2. Add the fish food or the chopped up raw shrimp/fish into the aquarium. Try to spread them out as evenly as possible. There is no need to hold back on the dosage since there is no live fish in the tank. Just use your common sense for not overdoing it.

Step 3. Since this is still the stage one, we are waiting for ammonia to appear. Test the aquarium water for only ammonia every day after three days into the fish tank cycling. There is no need to test it on the first a few days since it takes time for the organic matters (fish food, raw shrimp/fish) to break down into ammonia.

Step 4. Once you start to get a reading of ammonia, it has just entered the second stage. You should add more fish food or raw fish/shrimp into the tank, but the amount should be less than the first dosage. In the case of fish food, just dose as much as the amount you would have used to feed to the fish every day. You should also start to test for both ammonia and nitrite from this point on.

Step 5. If the ammonia gets above 6ppm which is a toxic level for even the beneficial bacteria, you need to do a partial water change to lower it back to 6ppm or less. The partial water change should not include gravel vacuum because you still need the organic matters at the bottom to produce ammonia on a constant basis.

Step 6. Continue to dose fish food or raw fish/shrimp in small quantity every day, and testing the aquarium water for ammonia and nitrite.

Step 7. Once you get a reading on nitrite, the fishless cycling has entered the third stage. You must test for ammonia, nitrite, and nitrate on a daily basis, and continue to add fish food or whatever you were using as a source of ammonia.

Step 8. As soon as you start to get a reading on nitrate, it has entered the final and fourth stage. You must begin to test the water for PH in addition to ammonia, nitrite, and nitrate on a daily basis. Nitrate production process can be acidic. It eats away the water buffer slowly and can cause a sudden crash of PH. When the aquarium water is too acidic, it can stall the cycle because it is undesirable for the beneficial bacteria. On the first sign of PH dropping, you should do a partial water change to restore the water buffer and to remove the nitrate.

Step 9. Continue to dose the fish food on a daily basis and test the aquarium water for all readings. Once you get 0ppm on ammonia and nitrite a few days in a row, the aquarium cycle is complete.

Step 10. Since you have cycled a fish tank with organic matters, there is a lot of phosphate in the water. You need to do several large partial water changes to get rid of most of the phosphate as well as nitrate before you can safely add fish. During the partial water change, you need to use the gravel vacuum to remove all the remaining organic matters at the bottom of the tank.

When you add fish, it is recommended not to add too many fish at once. Add a few fish every two to three weeks until you have fully stocked the aquarium is the best way to do it. You need to test the water for ammonia and nitrite every day as soon as you get the fish. If there is a sign of ammonia or nitrite, a large partial water change is recommended every other day with Prime as the water conditioner.

Cycling with fish food can be a lot slower than cycling with pure ammonia, but it is still just as safe for your fish since you cycle the tank before you add the fish. The whole cycling process can take more than two months with fish food. There are some tips for tank cycling can be used to reduce significantly the time required.

Fishless Cycling with Ammonia in Home Aquariums

What is fishless cycling?
To have sufficient amount of good bacteria in a new aquarium for the natural occurring aquarium nitrogen cycle, we must cycle the aquarium.  Otherwise, the fish will die. The methods to cycle aquariums without any fish are what we call fishless cycle. As the opposite to cycle an aquarium with fish, fishless cycling is more humane.   No fish will die in the process. While there is more than one way to fishless cycling an aquarium, one of the fastest ways is to use pure ammonia.

There are two ways to do a fishless cycle.
A. Use pure ammonia.
B. Use fish food, or raw fish/shrimp.

In this article, we will cover the pure ammonia method. Another advantage of using pure ammonia to cycling a fish tank is to have the option of fully stock your tank with fish in one go after the cycle is complete.

Whatever method you decide to use for cycling aquarium, you must set up an aquarium first. We will not get into details on how to set up an aquarium here.
Here is a quick list of the items you need.
1. A fish tank.
2. An aquarium filter.
3. An aquarium heater (if you will get tropical fish).
4. An air pump and its accessories.
5. An aquarium water conditioner.
6. A water test kit.
7. A source of pure ammonia.

Aside the necessary equipment to set up an aquarium, the only two other items here specifically for fishless cycling are the water test kit and a source of ammonia.

The water test kit
The only way to know how much ammonia, nitrite, and nitrate are there in the water is to test the water with a test kit. There are many different aquarium water test kits out there. One thing you must know is that liquid test kits are much more accurate than paper strip test kits. The latter is considered worthless for aquarium water testing by many people. The most commonly used water test kit is the API Freshwater Master Kit. It is capable of testing ammonia, nitrite, nitrate, and PH. There is enough supply in one package for more than 150 tests. A single kit should be sufficient enough for you to complete aquarium cycling with still plenty to spare.

A source of ammonia
We can use some commercially available bottled ammonia for fishless cycling. Whatever the source of ammonia is, you must make sure there is no additive in the bottle. Check out the ingredients is essential. The only thing you need in the bottle is a form of ammonia compound and water. Some ammonia products have soap in them, which makes them entirely useless for cycling a fish tank. One of the pure ammonia products I have used successfully is Ace Ammonia Janitorial Strength Formula. It is consist of 90% water and 10% ammonia hydroxide. Another type of ammonia I have used is Ammonium Chloride Solution by Dr. Tim’s Aquatics, while this is a much smaller bottle it is more than enough to cycle quite a few fish tanks.

Important things to know before you start the cycle
Although the beneficial bacteria you want to grow in your new aquarium is waterborne, they can only increase in sufficient number to colonize surface areas within your fish tank. The most surface areas available in an aquarium are in the filter media. Therefore, cycling an aquarium is cycling the aquarium filter system, since it is where the majority of your beneficial bacteria will be. You must make sure to run your filter system 24/7, and it must be rated high enough for your tank size or it will never have sufficient surface areas in its filter media to have enough bacteria for taking care of the ammonia produced by your fish.

A newly set up empty fish tank is doing fishless cycling with pure ammonia

A plated aquarium during fishless cycling
The Three Stages of a Fishless cycling

Stage One“Growing” Nitrosomonas

Define Stage: This is the stage where you will only find a reading on ammonia, while nitrite and nitrate both remain at 0ppm all the time. It requires the most patience because it can be the longest stage with no sign of progress.

Goal: To get a reading on nitrite is what you should be after for this stage. By the time there is nitrite in the water, it means you already have a large quantity of Nitrosomonas to convert ammonia.

Tasks: After the tank is set up and everything (filter, heater, air pump) is running, you need to add some ammonia to the aquarium water. While there is no need for absolute accuracy when you drop ammonia, the general rule is not to add more than 6ppm. Too much ammonia can even be toxic to the good bacteria, and it will stall the aquarium cycling.

You need to test aquarium water every a few days for ammonia and nitrite. To make sure there is always ammonia in the water, and to check the sign of nitrite to get an idea of how far the fish tank cycling has gone. It can take up to 2~3 weeks before there is even a sign of nitrite.

Stage Two“Growing” Nitrobacter

Define stage: Once you get a reading of nitrite, it has entered stage two. Now the second group of beneficial bacteria Nitrobacter will start to grow since there is finally food available to them. Nitrobacter would not grow during stage one because there was no nitrite available for them to feed on.

Goal: To get a reading on nitrate. You have to wait for Nitrobacter to grow into sufficient number before there is a sign of nitrate, and during this stage, this is precisely what you want.

Tasks: You will need to test the water daily to make sure there is always ammonia in the water, or the Nitrosomonas grew during stage one will start to starve once they have converted all available ammonia to nitrite. This stage is usually shorter than the second stage, but it can still take up to weeks before the next ste[, where nitrate is finally showing up on test results.

Stage ThreeWait to reach a balance
Define Stage: As soon as you get a reading on nitrate, the fishless cycling has entered its final stage. Now there are a lot of both Nitrosomonas and Nitrobacter in the fish tank to convert both ammonia and nitrite.

Goal: To get 0ppm reading on both ammonia and nitrite. To achieve a balance between the two different species of good bacteria to convert all your daily dosage of ammonia into nitrate without a trace of ammonia and nitrite at the end of the day.

Tasks – You should continue to test the aquarium water on daily basis to make sure there is always ammonia to start each day with. You also must keep eyes on the nitrate concentration and PH at this point. During this stage, water buffer gets eaten away slowly.  As a result, the PH might suddenly crash. When the PH is too acidic, it can stall the fishless cycle. As soon as you see a drop in the PH, you should do a large water change to reduce the nitrate and to restore the water buffer as well as the PH.

You also must set your goal of how much ammonia you want your aquarium to be able to handle when it is complete. If you wish your tank to convert 2ppm of ammonia daily, you must make sure there is 2ppm ammonia in the water every day after you just gave a new dosage.  In general, convert 2ppm ammonia daily can only ensure a light stock of fish.  Therefore, if you want to fully stock your tank at once, you need to aim for 5~6ppm ammonia being converted daily.

This stage should be relatively quick. It usually finishes within a week or so. Once you get a reading of 0ppm for both ammonia and nitrite a few days in a row while you still added ammonia 24 hours ago, the tank is fully cycled! You may add fish after one or more large partial water change to remove most of the nitrate.

Fishless cycling can be a slow and painful process for many people. Patience is required. The usual amount of time needed to cycle a fish tank can be six weeks or more. Exactly time required can be different on the case by case basis depending on many facts. There are some useful tips to speed up fish tank cycling and cut the time required to as short as a week or less in some cases.

Cycle with Fish (fish-in cycle)

Cycle with fish in the aquarium is one of the options of fish tank cycling.  It is also known as the fish-in cycle.

Why we must cycle fish tanks

Aquarium nitrogen cycle is essential for the survival of pet fish in a home aquarium. No fish can live for long in a new aquarium before it is cycled because the toxic ammonia will build up from decay organic matters in the aquarium as well as from fish gills directly.

To ensure an ammonia free aquarium, we must cycle all new fish tanks. There is more than one way to cycle a fish tank. While we highly recommend a fishless cycling.

We must have a constant source of ammonia to start the aquarium nitrogen cycle.  The fish themselves are a source of ammonia since they produce it on a continuous basis. Therefore you can cycle the fish tank with fish.  Cycle with fish can be successful only if we do it correctly.

To cycle with fish, you first need to set up an aquarium with all the necessary equipment and supplies.

1. A fish tank of the proper size for your fish.
2. An adequate aquarium filter system.
3. An aquarium heater.
4. An aquarium air pump and accessories.
5. An aquarium water conditioner.
6. A few 5-gallon water buckets.
7. A gravel vacuum.
8. An aquarium water test kit.

Things to do and to know before starting a fish-in cycle

You have to set up an aquarium first

Everything must be running before you add the fish.

The less fish, the better

You should add as few fishes as possible. More fish will not cycle the tank faster. Instead, more fish means quicker ammonia building up, and the fish will be more likely to die before it can complete the cycle.

Choose your fish species wisely

To cycle with fish, you must choose the right fish. The fish for cycling a tank must not all die before the cycle is complete. Traditionally people like to select a few “expendable” hardy fish to cycle an aquarium.

Zebra Danios are known for being able to survive in terrible water conditions for a while, and therefore they are one of the most common fish-in cycle candidates. However, Zebra Danios are known nippers. They are not compatible with longfin and slow-moving fish. If you have the plan to get such fish after cycling the tank without a plan to get rid of the Danios, you should use another species instead. Platies and guppies are also often used for fish-in cycling. Whatever fish species you plan to use for cycling a tank, they must be hardy.  At the same time compatible with the future fish you expect to get since you want them to survive long enough to complete the fish-in cycle.

Use an aquarium water conditioner that can detoxify ammonia

It is highly recommended to use SeaChem Prime as your water conditioner. Since you will have fish in an uncycled tank, ammonia will build up. Any trace of ammonia is harmful to the fish. Therefore the fish need your help to live through the fish-in cycle. Aside from the primary function of neutralizing chlorine and chloramine in the tap water, SeaChem Prime has a secondary function of detoxifying ammonia and turn it into harmless ammonium for up to 48 hours. This feature alone can make sure the fish will not be exposed to ammonia poisoning within 48 hours after each water change with Prime. As long as you do a partial water change with Prime every other day, the ammonia damage to your fish should be minimal.

Feed as little as possible during the fish-in cycle.

More fish food means more ammonia in the system. More ammonia will not help the fish-in cycle.  Instead, it might kill the fish faster. Once the fish is dead, you can’t continue the fish-in cycle.  We recommend feeding lightly every other day during fish-in cycling.

Steps of Fish-in Cycling

Make sure everything is working properly

To cycle with fish, first, you must make sure the filter is running.  The heater is providing the right water temperature, and the air pump is producing bubbles.

Add Fish

Add as few fishes as possible into your prepared aquarium.  Too many fish can produce too much ammonia which will kill the fish rather quickly.  The whole idea of the cycling with fish is to have the fish stay alive until the cycle is complete.

Test the water every day for ammonia and nitrite

Test the water every day for ammonia and nitrite. Since the tank is uncycled, you will be able to pick up a small trace of ammonia reasonably quick (usually in a day or two). If you have used SeaChem Prime as the water conditioner, the reading you get should be ammonium instead of ammonia.

Partial water changes every day

As soon as you discovered ammonia or ammonium in the water, you need to do a 30~50% partial water change every other day with Prime as the water conditioner.  By doing so, it should ensure your fish won’t die to ammonia poisoning before the aquarium cycle can finish. It will also keep the ammonia/ammonium level in check since more ammonia/ammonium will not make the aquarium cycle faster. It can take more than three weeks before the next step.

Test for nitrate

Once you pick up nitrite, you are at least one-third way into the cycling. It is a good sign, but do not cut back on partial water changes. From this point on, you should also test for nitrate in addition to ammonia and nitrite tests on a daily basis. It might take weeks more to get a nitrate reading.

Reduce the partial water change

Once you get a reading on nitrate, the final stage has arrived. At this point, you still need to do it every other day with Prime, but you can cut back on the percentage of water changed. For example, if you were doing a 50% partial water change every other day, now you may reduce it to 20% instead.  It is due to the fact you already have plenty of bacteria, and they have an increasing appetite for ammonia and nitrite.  Too much partial water change will limit their food source.  Therefore, it will slow their growth.

Reduce partial water change down to once per week

The day you get a 0ppm reading on both ammonia and nitrite, you should stop doing the partial water change every other day. Furthermore, you only need to do a partial water change once a week to lower the nitrate concentration.  It is to ensure the developing beneficial bacteria to have enough ammonia and nitrite to convert. The goal at this stage is to get 0ppm on both ammonia and nitrite.

Continue test for ammonia and nitrite, and start feeding fish every day

Wait for at least three days in a row after you begin to get 0ppm readings on both ammonia and nitrite. You may begin to feed your fish every day instead of every other day.  It will ensure regular production of ammonia by the fish, and as a result, the beneficial bacteria will also increase in quantity.

Cycle with fish is complete

Wait at least another three days before you can finally call it “the tank is cycled” if you continue to get 0ppm ammonia and 0ppm nitrite readings. Congratulations!

You may add more fish now but do it slowly

Introduce too many fish at once can still produce ammonia spike in an aquarium you just cycled with fish. It is a good idea to add no more than one fish at a time if you had only one fish in the tank by the end of the fish-in cycle.

If you have more than one fish survived the fish-in cycle, it is still a good idea to add only 1/3 of the existing number of fish at a time. In both cases, please wait for at least a week or two before you add more fish. You must also continue to do testing on the aquarium water for ammonia, nitrite, and nitrate. If there is any sign of ammonia or nitrite, you must immediately do a partial water change with Prime, and repeat it every 48 hours until there are no more ammonia and nitrite.

The advantage of cycle with fish

You get to have the pet fish immediately after you set up your aquarium. Many people can’t wait to get their hands on the fish the moment they set up their aquariums.  Therefore, we can see it as an advantage for some people.

The disadvantage of cycling with fish

You will expose your fish to ammonia poisoning during the fish-in cycle. The fish you use for cycling the aquarium might not survive.

There is a lot more workload because of the frequent partial water change required to sustain the fish through the tank cycle.

Cycle with fish is usually slower than fishless cycling. You will, in fact, wait longer before you can fully stock your fish tank.

There is no exact set time for the fish-in cycle just like fishless cycle due to too many variables in different tanks. You can certainly speed the process up and cut down the time required by applying some fish tank cycling tips. Although not guaranteed, some of the suggestions might cut down the aquarium cycle time to as short as a week or just a few days.