The Nitrogen Cycle

What it Is, and Why It’s Important

What is the Nitrogen Cycle?

Well, to answer the question of how the nitrogen cycle is important, it’s important to know what the nitrogen cycle even is! The nitrogen cycle is essentially the process of breaking down waste in your aquarium using something known as ‘beneficial bacteria’.


It starts with ammonia. When waste is introduced into an aquarium, it will slowly build up.If the pH is not at 7 or above, something called ammonium will form, which is non toxic, but also not essential to the nitrogen cycle. What you want is ammonia, which is toxic to form. It sounds counter-productive, but it makes sense, as the bacteria that you want to develop only wants to eat ammonia, which is only formed at pH levels of 7 or more. This bacteria is crucial for the next stage of the nitrogen cycle to occur.

This bacteria, known as ‘nitrosomonas’, will slowly eat away at the ammonia. Soon enough, you will have a colony of nitrosomonas living in your tank. As the colony grows, and more bacteria eat and poop, they oxidize the ammonia. This oxidization process of the ammonia produces the next stage of the cycle: Nitrites!


So, you have a bunch of bacteria chowing down on ammonia, and they’re producing a waste called nitrites. This is good! However, the nitrites that the nitrosomona bacteria produced is still highly toxic, just not as toxic as the ammonia that the nitrosomonas are dealing with. You don’t want to have this nitrite in your tank. So what do you do? You wait. See, as the nitrite levels begin to rise, another form of bacteria will form. This bacteria is known as nitrobacter.

As nitrobacter forms, they will start converting the nitrates in your tank into nitrate.


Nitrates are the final products of the nitrogen cycle. These are least harmful to your jellies, but they still pose a risk if they get out of hand. You’ll want to keep a close eye on these.

So How Do You Start the Cycle? How Do You Monitor It?

Starting the Cycle

To start the nitrogen cycle in your tank, you first have to make the water for your jellyfish tank. We have a blog post on how to mix saltwater for your tank, so, you know, check it out (please). Or there’s plenty of youtube videos, wikihow articles, or just generally informative websites that can teach you how to mix water for your tank. In fact, before reading on, please go and check out a source on how to make the water. I can wait. Trust me, I have time.

You’re back? You know how to make saltwater? Good because you’re going to need it. Fill your tank with it, and introduce a source of ammonia. Now, some people would encourage you to throw a fish in your tank, but this is considered by most inhumane. Not only that, but as you (better be!) dealing with saltwater, you may notice that saltwater fish are very expensive. Not only that, but once your tank is cycled, you can’t exactly keep jellyfish and regular fish together. So, putting a fish in your tank just isn’t a viable option. So what next?

Well, you can use a method known as ‘fishless cycling’. To do this, you introduce ammonia by adding in some fish food. Just as much as you would add if you had fish in the tank. If someone is confused by what you’re doing, just tell them you have invisible fish. When you leave the food in the tank, it decomposes into ammonia. You can add some extra food (again, as much as you would use in a regular feeding) about every twelve hours.

And with that, you have started the cycle! Congratulations! But, you aren’t finished yet, as you know! You have to maintain the cycle!

Maintaining the Cycle

So, you have ammonia in your tank. Now you have to figure out how much ammonia is in your tank. How? By using a test kit! You can use a test kit from our starter kit, or you can purchase a test kit online or in your local pet store. We like to use the Seachem Marine MultiTest kit to test our tanks, but the API test strips are just fine as well. What you’re looking for is to have the ammonia levels at around 3ppm (parts per million). If you see the ammonia levels drop, add some more fish food, and try to keep the readings stable for about a week. It’s okay if the readings aren’t always at 3ppm, but that’s what you’re aiming for.
So a week has passed, and you’ve been trying your best to keep ammonia levels stable. Now, it’s time to start testing for nitrites! As soon as you get your first reading of nitrites, you’ll know the cycle has begun.

At this point, you’ll want to keep adding the fish food occasionally, but you’ll notice the levels of nitrites will steadily rise. However, after another week or so, they’ll start dropping. Now is the time to test for nitrates. I’d also take this time to celebrate, as at this point, the cycle is nearly complete! You’ll have jellyfish in no time!

But, you have to keep testing the water! Do this every day, and be patient. This process could take another week or so. However, your patience will be rewarded! Once the ammonia and nitrite levels are at 0, your cycle is complete! That said, if your nitrates are over 40ppm, you’ll want to do a partial water change to bring the levels down.

So What’s Next?

So now your tank is reading 0 ammonia, 0 nitrites, and less than 40ppm of nitrates. What’s next? You have worked hard to get your tank set up for over two weeks now. It might have even been a month by this point! But, your work has paid off.

At this point, it’s time to visit to pick up your new jelly friends!

Our Sources:


Our Kits and Packages

Jellyfish Aquarium believes that customers deserve the best quality items to maintain their jellyfish tanks. For this reason, we have created two separate packages that we consider essential for caring for your jellyfish.

The Pro Maintenance Kit includes all the equipment you need to clean your jellyfish tank.

The first package to cover is the one that is essential for cleaning your tank. This package is the ‘Pro Maintenance Kit’, which you can find on our website store under the ‘Kits’ category. This kit includes a small siphon, an acrylic-safe algae scrub pad, an acrylic-safe cleaning cloth, and something we’ve coined the ‘Jelly-Thing Tool’. All of these tools are used together to keep your tank spotless. These tools are also all available individually under our Cleaning Equipment tab, located under Equipment in the shop categories. This kit is needed to care for the tank, and maintain the water quality. Thankfully, this package is generally a one-time purchase, as you’re only purchasing tools.

The Quarterly Supply Package has everything you need to feed and care for your jellyfish friends.

The second package includes all the supplies to care for the jellyfish themselves. Our ‘Quarterly Supply Package’ for a 2 gallon tank includes 25g of dry jellyfish food, 10 gallons of jellyfish salt, 1 pack of Chemipure Blue (Nano Sized), and 100ml of Seachem Pristine for biomaitenance. There is a variant of this kit that also includes API 5in1 test strips to check how healthy your water is for your jellyfish. These kits are absolutely essential for caring for your jellyfish, from feeding them to giving them water. We strongly recommend that you purchase this kit to give your jellyfish the best life possible.

At Jellyfish Aquarium, we take care of our jellyfish to the best of our ability. We know that with these packages, you will be prepared to give your jellyfish a long and healthy life as well.

Pro Maintenance Kit:

Quarterly Supply Package:

Quarterly Supply Package with Test Strips: