How to Lower Nitrites in Saltwater Aquarium

Many different things can go wrong with your saltwater aquarium. For example, you may not be aware of high nitrate levels in the water column or substrate. Nitrates, created by livestock waste and excess food, will eventually break down into ammonia and then nitrite.

How to Lower Nitrites in Saltwater Aquarium

This is a problem because nitrites inhibit photosynthesis which means algae growth slows down or stops altogether. Once this happens, it’s hard to get it back, so I will tell you how to lower nitrates in saltwater aquariums! In this article, we’ll explore how to lower nitrites in saltwater aquariums.

Step to Follow on How to Lower Nitrites in Saltwater Aquarium

Step One: Determine

First, determine the level of your nitrites. In a fresh saltwater aquarium, nitrite levels should be zero. However, as time passes and organic material is present, the nitrite levels will climb to detectable amounts. If you have been monitoring your tank’s water condition regularly using a quality test kit, you can base this determination on past results for your aquarium.

If you are unsure of your nitrite levels, it is best to test the water before beginning the process of lowering nitrate levels. This will enable you to see your rate of progress towards a nitrite-free saltwater aquarium. However, even if you are unsure of your current levels, some basic tips are outlined below that can help negate or reduce nitrites in an established tank.

Lower Nitrites in  Saltwater Aquarium

Step Two: Take Necessary Steps

It is important to remember that nitrite levels will rise over time. This is because nitrifying bacteria present in an aquarium act on ammonia and produce nitrites. If you are adding new fish, your tank cannot handle the extra bioload of the fish until it has had an opportunity to build up enough beneficial bacteria to convert the increased ammonia.

Do not add new fish until your nitrite level has dropped below detectable levels. If you are performing water changes, be sure to use a quality de-chlorinator to remove any harmful chlorine or chloramines in the tap water. As salt mixes contain a small amount of nitrite, be sure to rinse the salt before adding it to your tank thoroughly.

Step Three: Reduce Your Bacteria Inhabitants

There are various nitrifying bacteria present in your aquarium, both inside the live rock and within the sand bed. These surfaces act as a dynamic biological filter where nitrate is converted to nitrogen gas, drastically reducing nitrate levels in an established tank.

If you have large quantities of nuisance algae in your tank, removing this from the aquarium may be wise. As algae play a pivotal role in the nitrogen cycle, removing large amounts of it will decrease your bacteria population and can make a big difference in lowering nitrate levels.

Step Four: Perform Regular Water Changes

As your aquarium matures, water changes will play an important role in lowering nitrate levels. As anaerobic bacteria break down organic material within the gravel and live rock, the nitrate levels will rise. Water changes will remove this organic material and reduce your nitrate levels.

Regular water changes are also necessary if you are housing corals within the aquarium. Nitrates can inhibit calcification, which is an important part of healthy coral growth. If you reduce the bioload in your tank by removing nuisance algae, you should also reduce the bioload by performing smaller water changes more frequently.

Step Five: Test Your Water Condition Regularly

Regular ammonia, nitrite, and nitrate testing can help make a big difference in lowering your nitrates. As your tank matures and bacteria colonies begin to grow, the addition of new fish will not overload the bioload as quickly. However, continuously testing for ammonia and nitrite levels will assist in this process.

Always be sure to test your tap water and the aquarium water before beginning a routine of lower nitrates. This will allow you to determine if any harmful chemicals within your tap water may inhibit the progress you are attempting to make. In addition, these steps should help you in learning how to lower nitrites in saltwater aquarium.

Step Six: Add More Live Rock

Live rock will play a role in naturally reducing nitrates within your aquarium. As anaerobic bacteria convert the ammonia and nitrite into nitrogen gas, adding more live rock can help aid this process. However, be sure that you are not overstocking your tank with fish before adding live rock.

If you are overstocking your tank, the initial ammonia spike will not allow the bacteria to grow quickly enough to keep up with the bioload. The result will be an aquarium that is overwhelmed by nitrites and low oxygen levels, which can lead to disease and death within your tank.

Step Seven: Limit Feeding

Limiting the amount of food you feed your fish will help reduce the bioload. In addition to this, as food is broken down, it can release additional ammonia and nitrites into your aquarium, resulting in a cycle that might be difficult to break. Therefore, foods such as brine shrimp should be fed sparingly to your fish and should be explicitly designed for marine aquariums.

Perform Regular  Water Changes

If you purchase frozen foods, be sure that your brand does not contain any added phosphates. This can be very detrimental to your aquarium and lead to an explosion in algae growth. If you are experiencing high nitrates within your tank, try limiting the amount of food that is introduced into your aquarium.

Step Eight: Limit Organics

As previously mentioned, organics can be broken down by anaerobic bacteria within your gravel and live rock. This will result in the production of additional nitrites, which are also harmful to fish. Therefore, organic mulm built upon the aquarium floor should be removed regularly to limit its accumulation.

Be sure that you are performing your regular water changes to remove organic debris. If your tank cannot maintain a balance between the nitrogen cycle and organics, consider doing more frequent, more minor water changes to keep nitrates at bay.

Step Nine: Limit Light

To create a stable environment that is not overpopulated with organics, you should consider limiting the amount of light within your tank. If there are high organics within the gravel or substrate, the light will encourage their growth.

Limiting the amount of time your aquarium lights are turned on each day can also help in reducing the bioload. However, if your aquarium is heavily planted, you should be sure that your plants receive enough light to grow. This will help in how to lower nitrites in saltwater aquariums.

Step Ten: Reduce the Biodiversity Within Your Tank

Removing some of the fish from your tank can help reduce nitrates and improve water quality. This process is known as fish-in cycling, and it involves gradually lowering the number of fish in your tank for several weeks.

Reduce the Biodiversity

This is a very stressful process for your fish and can result in high ammonia levels within your tank. If you are going to try this method, be sure to closely monitor your ammonia and nitrite levels. Remember, this is not recommended for tanks with a heavy bioload or tanks with sensitive fish species such as seahorses.

Frequently Asked Question

What Is the Fastest Way to Lower Nitrates in an Aquarium?

The best way to lower nitrates in an aquarium is by using a filter that can remove nitrogenous waste. However, if you are not able to install a filter, the second-best option is water changes.

What Removes Nitrates From Saltwater Aquarium?

Nitrates are toxic to fish and other marine life. They may be present in your aquarium as a result of fertilizer or water treatment processes.

The best way to remove nitrates from the saltwater aquarium is by using activated carbon, which can absorb nitrates from the water and help prevent them from accumulating in the aquarium.

Some alternatives include adding a liquid carbon filter to your freshwater tank or using dry carbon in an air pump filter.

Does Distilling Water Remove Nitrates?

No, distilling water does not remove nitrates. Distillation is a process that uses heat and pressure to purify liquids or gases by removing impurities.

How Long Can Fish Live With High Nitrites?

Fish can live with high nitrites for about 10 days, but it is better to use a different type of fish than what you usually use. It is important to note that if you want to keep the fish alive for more than 10 days, then it would be best to keep them in an aquarium and not in your tank.


There are a few things you can do to lower nitrates in your saltwater aquarium. The first is to make sure that the filter system is running correctly and has been cleaned regularly. Second, it would help reduce the amount of food you feed your fish, as this will help reduce waste production in the tank.

One last thing would be to replace some water with distilled water, which helps remove nitrogenous wastes from the tank. The conclusion paragraph is informative and provides information on how to lower nitrites in saltwater aquariums.

You can also check it out: How to Add Calcium to Freshwater Aquarium

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