How To Lower Nitrate Levels In Saltwater Aquarium

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Controlling the nitrate levels in your saltwater home aquarium is always a problem, and many reef-keepers have trouble with it. Keeping your aquarium water at safe nitrate levels will take some effort from your side and starts at the beginning.

We will take you through the steps on how to lower nitrate levels and how to prevent them from rising too high. There are a number of ways to lower the nitrate in your saltwater aquarium so we will take a look at the most effective methods.

If you are one of those who have trouble with nitrate in your home aquarium, keep on reading and learn to manage it.

What Is Nitrate?

Nitrate occurs in the saltwater of your aquarium because of fish food, waste, and other types of organic matter. All that matter is broken down by bacteria in the water and the by-product is nitrate, which is dissolved into the water.

There are two types of nitrates in a saltwater aquarium – organic nitrate, and dissolved nitrate, and that’s what you test for.

How To Measure Nitrate Levels

The best way to test the nitrate levels in your saltwater aquarium to know if you need to do some action to lower nitrate levels is to make use of a home water testing kit. It is also recommended that you test for nitrate levels and phosphates at the same time so you can manage them easier.

These tests should be done every one to two weeks or whenever you change the water so you can monitor the nitrate levels.

In naturally occurring reefs in the ocean, the nitrate level is around 0.1 parts per million but that is not possible to obtain. Some reef-keepers maintain a healthy home aquarium with nitrate levels above 10ppm without experiencing any problems with the environment.

It is recommended that you keep the nitrate levels as low as possible, with the best level being around 2ppm. To be on the safe side you should keep the nitrate level at 2ppm and not higher than 5ppm for a healthy environment.

How To Lower Nitrate Levels

As mentioned there are many ways to lower nitrate levels in your saltwater fish tank, so let’s look at them.

Change the Water

If you have a high-nitrate problem in your home saltwater aquarium you can change the contaminated water with a fresh supply. This can be used as a temporary solution to lower nitrate levels but you will have to repeat it every time you have it high.

It is the easiest and quickest method to lower nitrate levels but you need to find the reason why you have high nitrate levels in your aquarium water. By replacing the contaminated water with better quality water, you will lower the concentration of nitrates in the saltwater tank.

You should also take care that the water you use to replace it also has low nitrate levels, to begin with. A standard water change of 20 percent will not really lower the nitrate levels so you need to completely replace the water.

How To Lower Nitrate Levels In Saltwater Aquarium

Use Chemicals

Using the proper chemicals in your saltwater home aquarium to lower nitrate levels will also address other problems in the water of your tank. This method will easily treat other chemical imbalances and the core of the nitrate level problems you have in your aquarium.

Most aquarium nitrate-removal chemicals will lower nitrate levels but not help cure the reason for the high levels of nitrate in the fish tank water. The only way this method will be effective not only to maintain lower nitrate levels is to use it together with a protein skimmer that is already working in your aquarium system.

Nitrate Reactor

This is a device that can be used to directly remove the nitrate contaminants from the water in your home aquarium. How it works is to run a low flow of water through this system and it will then remove the oxygen from water.

This will, in turn, promote algae growth which will then consume the nitrates in the water and in the process lower nitrate levels. This process will turn the nitrates into nitrate gas which is then released into the atmosphere, and your water will be healthier.

Make sure that the nitrate level is lower in the reactor chamber than it is in the water of your fish tank. This way you can be sure that the reactor system is working and doing what it is meant to do.

Make Use Of the Refugium Method

This method makes use of a mini aquarium that is placed under the main tank that contains macroalgae and live rock. A sand bed can also be included with the refugium to increase the chances of removing nitrates from the water.

This water will then be circulated through this tank where the nitrates will be removed and pumped back into your aquarium. When using a refugium you must make sure it has the appropriate lighting to help the algae grow quicker.

When you remove the algae from the mini tank, the nitrates will come with it and the nitrate level in your water will be lower.

Bio Pellet Reactor

This is one of the most effective methods to remove nitrates from the water of your saltwater home aquarium. These pellets are basically bacteria that break down and at the same time lower the nitrate levels in the water in your tank.

All this happens while the water is continuously pumped through the reactor and recycled back into the water of your home aquarium. This method, combined with an effective protein skimmer, will help keep the nitrate levels in your fish tank at the lowest levels.

How To Prevent High Nitrate Levels

The best way to prevent the nitrate levels from rising too high is to start with the water added to your home aquarium. A good way to do this is to make use of a reverse osmosis system to clean the water before you add it to your tank.

For further information on how to lower and prevent high levels of nitrates in your aquarium water see the following Youtube video.


As you can see, it is better to prevent high levels of nitrates in your home aquarium by starting with the water you add. Hopefully, this article will help you solve the nitrate issues in your home saltwater aquarium for a much healthier environment for your pet fish.

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