The Fish Tank Nitrogen Cycle - Why it’s Important and How it Works - Fishless Aquarium Cycling With Ammonia

 Fish tanks are exciting! Once you get one, the urge is almost always immediate to start looking for an upgrade. This is great! We love the aquarium hobby as much as you do (obviously…) but there are a few things you need to know before simply filling that tank with fish as the pet store guy told you to.

What is Aquarium Cycling?

Cycling a tank is the process of growing beneficial bacteria that help to regulate the environment inside your aquarium. Basically, you are attempting to recreate a natural ecosystem in a tiny little space. This sounds tricky, never underestimate the power of an aquarium though, people often don’t realize that there's a lot of hardcore science going on there! While not necessarily easy, we have figured out the best ways to recreate nature and keep happy and healthy aquatic life. Cycling is your first step. Don’t be overwhelmed if it seems like a steep learning curve, it’s done regularly in everyone’s aquarium and you’ll soon get the hang of it naturally.

What Cycling Does

As extra food, excrement and old plants break down they begin to form what is known as ammonia. Ammonia can take the form of a liquid or gas and is toxic to your aquarium inhabitants. To counter the deadly compound, you do need to keep your tank clean and not overfed or overstocked. 

Fish and plant waste are the first things that are going to build up in your aquatic system. Like your septic tank, these need to be removed before you end up with problems. In the case of aquariums, the toxicity that this waste puts off is deadly and will kill everything if not handled properly. 

Naturally, there is a way to get rid of ammonia, and that is in the way of bacterial growths that feed off the nasty stuff. As bacteria grow, they convert ammonia to nitrites. Nitrites are less toxic than ammonia but will still kill your fish. However, as nitrites build up another form of bacteria begins to grow that then converts these nitrites to nitrates, once this happens, your tank is safe for fish to live in. 

Moving forward, if too much waste is built up or the beneficial bacteria are harmed then your ammonia or nitrites can come back. As long as you keep your tank on a regular maintenance schedule and know that it is cycled you should continue to have a happy and healthy aquarium.

How to Cycle Your Aquarium Using Ammonia and No Fish

As a beginner, it is difficult to know exactly who is giving you good, bad or made-up advice. The fish store people mean well, sometimes, but don’t go solely off of what they say. We've heard too many times that all you have to do is add Quick Start, or some other cycler, for an instant cycle. This is not how it works. You might get lucky with a small tank and hardy fish but, in general, you are putting a strain on your fishes and are sure to have a lapse at some point. That being said, to safely, knowingly, and more ethically cycle a tank, these are the steps we recommend to create a living environment with ammonia:


Set up your tank and ensure that you have as much filter media as possible to begin growing bacteria. Depending on where you live, your water may be less or more toxic in the substances it contains. Chlorine is found in most tap water and will kill your fish. Once you’ve filled up your tank one of the first things you should do is add a dechlorinator to the water.


The next step is to start creating a cycle that will grow bacteria. Because there are no fish, we are going to add ammonia to get the process started. Add a few drops at a time and test your water until ammonia levels are up to 3-4ppm. Do this daily until you see your nitrite levels start to rise because this means that they are growing off of the ammonia and are processing it out.

This process can go anywhere from a few days to weeks, so have patience! It is advised to turn up your tank temperature too as bacteria like a warm environment to grow.

NOTE: It is at this point in the process where you may experience what is known as a bacterial bloom. The water may appear cloudy because of the amount of the bacteria that rapidly was produced during the cycling process. Don’t worry, it will go away on its own after a few days. This is a good sign in a fishless cycle!


The end goal here is to get your tank to zero ammonia and nitrites. Once these are to zero, your nitrate levels will be very high as this is the end process of the well and thriving bacteria. Large doses of nitrates are not good for your fish though, so you will want to do a 50%-80% water change to sort them out. Test water after each change/addition until you have zero ammonia and nitrites and very low nitrates. There will always be nitrates to some degree in your aquarium, just be sure to keep an eye on them and do water changes regularly.


Now that you’ve gotten to what should be a healthy environment, you get to start adding fish. It may be more convenient or fun for you to add all of your new inhabitants at once, however, a brand new aquarium should still be watched and taken care of slowly. Because of this, we recommend only adding a few fish at a time, especially on the first go-round. The reason being is that an increased bioload may disrupt your levels and cause an ammonia or nitrite spike overnight, and there’s nothing worse than waking up to a tank load of floating fish. 

Add a few of the hardier fish to start and test your levels for the next few days. As mentioned, there may be a spike, this is normal, simply treat it accordingly with water changes. Once you’ve gotten stable levels, feel free to add more and enjoy your hard work and patience!