This is one of the most important posts you will read for setting up a saltwater tank for beginners.

After deciding to start a saltwater aquarium, you’re anxious. You want saltwater fish in your aquarium the same day you buy your new saltwater aquarium, but this can’t happen and I will tell you why.

The saltwater aquarium hobby is delicate and not something you can rush. If you don’t follow the rules of nature in the saltwater aquarium hobby, you will not only lose money, but saltwater fish as well.

You can’t rush the setup of a new saltwater aquarium.

Saltwater fish breathe via oxygen in the water. If you put fish in your new saltwater aquarium within 30 days, they will die.

Never put fish in a new saltwater aquarium right away

When you first set up your saltwater aquarium, the biological filter is not ready to handle the waste the fish are producing (ammonia.)

Getting the biological filter up-to-speed for your new saltwater aquarium requires putting the tank through a process called cycling the aquarium. Cycling a new saltwater aquarium allows naturally-occurring and ubiquitous bacteria (beneficial bacteria) to populate the filter media in the aquarium.

The reason for saltwater fish dying in a new saltwater aquarium setup is ammonia poisoning!

Saltwater fish urination is ammonia. Ammonia in your saltwater aquarium is very bad, as it suffocates your saltwater fish, causes nerve damage and death.

The more fish you add to your new saltwater aquarium, the more ammonia you will have in your saltwater aquarium. It doesn’t take long for ammonia levels to reach dangerous levels (few days), even with a few new saltwater fish.

The more saltwater fish you add to your new saltwater aquarium, the more ammonia you will introduce to your new saltwater tank. Ammonia is very dangerous and your saltwater fish will die from ammonia poisoning (suffocation) if you don’t cycle your new saltwater aquarium.

How to remove ammonia from a saltwater aquarium

As I said, the saltwater aquarium hobby is a slow delicate process, but if you follow the rules of nature and take your time, you will be fine.

Bacteria is a bad thing, but in a saltwater aquarium, bacteria is a great thing! Bacteria breaks down ammonia in your saltwater aquarium.

Since beneficial bacteria breaks down ammonia in your saltwater aquarium, you must introduce bacteria into your new saltwater tank to start the process of what we call cycling your new saltwater aquarium. This is known as the Nitrogen cycle. I know it’s sounds complicated but it’s easy.

The beneficial bacteria begins processing the ammonia produced by the fish into harmless nitrate, which you can then remove with your regular, weekly 10-15% water changes.

Some people buy bacteria out of a bottle, which I have never done. I don’t rely on chemicals or a possibly expired bottle of bacteria to put in a new saltwater aquarium to start the bacteria cycle.

Once the sand, saltwater and rock scape are setup in your new aquarium, it’s time to start the saltwater tank cycling process. The cycling process for a new saltwater aquarium is the building up of beneficial bacteria so no ammonia is present in your tank.

When cycling a new saltwater aquarium, I place a half dozen shrimp from the butcher in a new saltwater aquarium. The shrimp (already dead when you buy them) will rot in the tank, creating ammonia, and then bacteria.

Some people have used live saltwater fish to start the cycle process of their new saltwater aquarium. This is inhumane and wrong.

As the shrimp rot, ammonia levels rise to toxic levels in your new saltwater aquarium. Bacteria also starts to form in the water column, in the sand and on the rocks of your saltwater tank.

You can test ammonia levels in your saltwater tank with an ammonia testing kit or an ammonia test badge. I love the ammonia test badges since they are very easy to read and require no setup.

An ammonia test badge is a small color-changing plastic disc that stays on your aquarium glass with a suction cup. This little ammonia badge lasts about a year and is one of the most valuable tools you can have for a new saltwater aquarium setup. I always keep one in the tank to monitor ammonia levels in the aquarium.

Ammonia levels will climb and spike over the course of a couple weeks in your new saltwater tank and then suddenly drop to zero.

Ammonia levels of zero after a few weeks mean the bacteria has grown to the point of removing all ammonia in your new saltwater aquarium.

Once ammonia levels are at zero, it is now time to place ONE SALTWATER FISH in your new saltwater aquarium.

You can only place one saltwater fish in your aquarium, or possibly 2 small saltwater fish, such as clown fish, in your saltwater aquarium. You don’t want to overload your new saltwater aquarium with a lot of ammonia (fish urine) by adding a bunch of fish all at once.

After adding one or two small saltwater fish, you may see ammonia levels rise slightly, from their urine, but more bacteria will breed and overpower this ammonia quickly, bringing the ammonia level to zero once again.

After a couple weeks have passed and ammonia is zero, you are now ready to add your third small saltwater fish to your new aquarium.

This is how the cycling process works for a new saltwater aquarium setup.

So many beginners in the saltwater aquarium hobby get all excited and want a bunch of saltwater fish in their new saltwater aquarium the same night their aquarium is setup. This results in dead fish over the course of a few days.

Ammonia is converted to nitrites and nitrites are converted to nitrates. Nitrates are removed with weekly water changes and a great protein skimmer. More posts on nitrites, nitrates and protein skimmers and what they are can be found on this site.

If you follow these steps to cycle your new saltwater aquarium and take your time, your saltwater tank will build enough beneficial bacteria to house the amount of saltwater fish you want.

Beneficial bacteria will continue to breed and grow through your tank. Beneficial bacteria lives in the rocks, on your aquarium sand, on the glass of the aquarium and everywhere. As fish food rots and fish waste builds up, beneficial bacteria will continue to thrive over time.

It’s important to never overfeed your fish, as extra rotting food caught in rocks and sand will cause nitrates, which are bad for saltwater fish and especially corals.

Remember to never stock your saltwater aquarium with too many fish. This will cause problems which I will discuss in another post.

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